New games in bold.

Panzer Dragoon Zwei is a 3D rail shooter that is a blast to play. I think for most in the Sega world, Panzer Dragoon doesn't need much of an introduction. Zwei is obviously the second entry in the Panzer Dragoon franchise and sticks to the rail shooter formula that is seen in 4 out of 5 of the Panzer Dragoon games.
Zwei is simple. You can either shoot like a mad man tapping away at your Saturn controller or you can attack gracefully using the lock-on ability. In addition, you come equipped with the option of unleashing a flurry of attacks known as the Berserk that automatically wipe out all foes on screen. In order to obtain this ability, you must charge your berserk meter enough to have the privilege of using it.
Zwei does introduce some other new twists to Panzer Dragoon. In Zwei, you now have the ability to evolve your dragon based on your performance in each episode, which makes Lagi larger and more powerful. Moreover, Zwei introduces path branching in each episode, which does add to the replay value of Panzer Dragoon Zwei.
Graphically, Zwei starts out morbid and drab. However, the later episodes have some truly breathtaking levels. They are far more impressive compared to the earlier episodes. For me, episode 6 really stands out as simply being the perfect fusion of beauty, magnificence and perhaps even elegance. You can tell that despite the limitations of the Saturn, the developers manged to squeeze every little trick to make this world come to life and seem convincing.

To that end, Zwei is also accompanied by a perfectly matched soundtrack that doesn't distract or over power everything else. In fact, it's so perfectly balanced that when you do listen closely, one cannot help but be impressed by the music.
The most dated aspect of Panzer Dragoon Zwei would have to be the intro and cutscene videos. The videos are using CG and are very rough and really dated by modern standards. This doesn't impact the fusion of story telling and gameplay that is so masterfully presented in Zwei. The game does this by having the early episodes entirely on foot since the Dragon, Lagi is new to this world. However, in the later episodes, the first dive that leads to Lagi's first flight is just brilliantly executed. Other than that, Zwei does hold up fairly well especially in terms of its excellent and frantic gameplay.
It's worth nothing that even after all of these years, Panzer Dragoon Zwei has managed to remain a Saturn exclusive (apparently it was on Gametap?). The game has not be re-released on XBLA, PSN or even under the Sega Ages label. It wasn't included in any compilations or even with Panzer Dragoon Orta. It's obvious that Panzer Dragoon Saga gets all of the attention but Zwei is an excellent addition to any Saturn owners collection.
IMPORT FRIENDLINESS:There is essentially no difference between the JPN and US versions of Zwei. The most obvious would be the cutscenes and intro which are subtitled in either Japanese or English depending on the version that you are playing. Other than that, the games are identical. It is worth noting that the voice overs are identical in both versions as the game has its own mysterious language crafted specifically for it. Other than that, the menus and everything else are in English. Very easy to play for any importer. As always, a quick trip to Youtube is recommended to fill in the story.
Price comparison: NTSC-J can be had for just a couple of dollars complete and mint.
NTSC-U goes for about $25+/- complete. It's going up in price like everything else that is US Saturn.