I'll start by saying that my initial introduction to the Mega Man franchise, and the source of most of my time investment in the games has all been in the X series, up to this point. I played a little bit of Mega Man 7 on an emulator in middle school (which I've never really liked) played a lot of Mega Man 8 (which is a game I've always really liked) and dabbled with various emulations of the original four or five NES titles. The original series has always seemed too unfriendly, and generally too difficult for me. (Mega Man 8 felt really gentle to me when I was younger, and I nearly beat Wily once, but was close to breaking shit after realizing that trying to continue later set me back at the beginning of the castle.)
Enter Rockman Mega World: This game is like a dream. Since really playing/trying any of the original Mega Man series, I've become more proficient in shmups and spent a lot of time with the Castlevania series. So, NES era Capcom games don't instill the same level of fear in me that they used to. I've been meaning to really sit down with the early games in the original series for a while, and Mega World seemed like a great way to get my feet wet with the series, so to speak, while skipping that loathsome NES hardware. Suffice it to say Mega World doesn't come cheap these days, but man, I think it might be worth it.
I'll get it out of the way by saying that I, personally, feel the Mega World ports are the definitive versions of the original three games. I'm well aware that anyone who grew up these games on the NES is probably about ready to pop a gasket after reading that. Let me use this opportunity to bring up the NES games: After completing Wily Tower in Mega World, I had the itch for more. So, the next day--still sans one internets--I decided to try out the NES versions. I'll note that I don't have any of the original carts, but for the purposes of reproducing NES games, I don't see emulation as that far off the mark. That said, the original Mega Man turned me off almost instantly. The "momentum" bases slide (which is also one thing I hate about 2d mario games) and the general increase in difficulty due to clunky, dated mechanics were an immediate turn off. I was not at all surprised that I wasn't really able to get into the original series, as I generally start playing series of games in chronological order of release. I made it as far as Elecman's stage--not even Elecman--before throwing in the towel. Incidentally I went Bombman->Cutman->Elecman, mistakenly skipping Gutsman because I had heard that Cutman is unfathomably easy in the NES version--only remembering that after beating Bombman--and tried switching orders.
At this point I switched to Mega Man 2 (hard mode) and felt fairly determined to beat it, just to prove to myself that I could. I ended up completing it in approximately the same amount of time it took me to beat it in Mega World, but it was not at all the same experience. While I don't entirely feel 2 is as marred by the clunky feel of the controls as the original is, the Mega World port is overall a much smoother, crisper, more flowing experience. Conversely, the NES version feels rough, jagged, and stiff. While playing through Mega World, I felt that the NES versions might have a leg up in controls, and after spending quality time with 2 on the NES, I would emphatically say that they are considerably less durable on the NES. While this may be due in part to the difference in controllers (wii remote vs JP MD 6-button pad; and don't tell me that the NES controller is better than the wii remote, because it is not) I feel it bears mentioning. Rock just does some funny (or not-so-funny, depending on the situation) things in the NES version, that don't crop up in the Mega World port at all. The most glaring instance was sliding physics popping up in Metal Man's stage between two of the spiked weights. I don't know what's going on in that stage, but in the NES version, I would land directly in the middle of the platform between them, yet slide into the second weight despite attempting to influence the controls to the left. That's a fairly extreme example, but I didn't have any issues of control in the Mega World port that weren't also an issue in the NES version. (eg restorative capsules messing up timing/input.) It bears mentioning that the biggest differences between ports is the aspect of speed: projectiles, for the most part, move more slowly in Mega World, making Rock's rate of fire much lower at times, and making certain boss fights like Heatman, a bit easier. (Although, with Heatman, it really doesn't matter unless one were doing a mega buster run.) Slowdown is also more apparent in Mega World, and especially noticeable in Woodman's boss battle. I found him to be just as difficult in Mega World as in the original--which is to say, not very, outside of a mega buster run. It really just changes the timing. I will say that the final boss fight in the Mega World port requires far less precision by comparison, as a result of the projectile issues. Although the Wily fight is far easier in the NES version, as the first form shoots in different patterns in the Mega World port.
Now on to IV. (Why? Because I said so.) Oh, dear lord. I don't know what happened. It's like someone slapped this game with poor level design, repeatedly, until it was battered and bloody, and just relented. Case in point: A route to an E-can in Brightman's stage having an extra life sitting right next to the E-can in order to make the player feel more confident in inevitably committing suicide. Sure, I might be able to rush coil, or if I had had it, rush jet my way back, but no thank you. This is a simple fix in design by just removing the lower platforms, and making the track-platforms green, or by putting the E-can in the top corner, removing the ceiling, raising the tracks, and narrowing the gaps between the lower platforms. There is way too much in this one that is explicitly designed to kill the player without any advanced warning. I haven't even seen Dustman because his stage is unadulterated bull shit. It's barely a notch above "Fan-hack."
So, let's get down to brass tax: I'll probably never bother to play the NES versions of Mega Man, Mega Man 2, or Mega Man 4, in any iteration, ever again. Rockman Mega World? I might play that tomorrow. Y'know, I rated Rockman 1/2/3 on backloggery individually as 4-stars, but as a package, Mega World is a perfect 5. My only gripes to speak of are that Rock seems to take a split second to stop inching forward and start running (which I will gladly take in comparison to the NES versions) and that the one original mode in Wily Tower doesn't seem like it's been given the same care, and attention to detail as the rest of the game. In general, it's still very good, and the features in the gameplay at that stage are very cool, but there are some textures in the greener scenery that just remind me of some of the worst graphics the Genesis can muster, and the graphics used in the menu screen are fairly lackluster. The robot masters are piss easy, too. Overall, Mega World/Wily Wars is an easy recommendation for me to make. Granted there are potentially some serious barriers to its enjoyment. So in that sense, I won't entirely blame people for defending the NES games, though I do think they're a generally less pleasant experience.
to make special mention of the music: Oh, man! The music! I've always generally respected the compositions of the music for the NES titles, but I find it undeniable that they lack something to be desired in the instrumentation of the 2A03. My beloved FM chip polishes these tracks up into sparkling diamonds, though. They were good before, but on the Mega Drive, they are superlative. Before words of hate start boiling, and bubbling from peoples mouths and fingers, I will concede that the charm inherent in the 2A03 does lend itself more to certain tracks like Wily Castle 1 in Mega Man 2, and consequently the YM 2612 rendition doesn't have quite the same driving feel to the bass line. (Which is pretty uncharacteristic.) Overall, I think the team at Capcom outdid themselves in translating the tracks from the original games to the YM 2612, and the tracks original to Mega World are really something too. Maybe not as classic as Rockman 3's title track, or the Bombman/Elecman/Metalman/Flashman stage themes, but still really solid stuff. I'm actually in the processes of recording all the tracks in the soundtest through the stereo audio out on the Wondermega, and encoding them as FLAC files. (Plus some minor touches in fade-outs and such.) I was thinking of putting together a release, but I'm a little cautious in doing so, at the moment.