I really like just about everything about this game. About the only thing I can say bad about this game is that it is pretty short, with 5 real stages and an End Boss, and the stages themselves are all rather short (although different paths may be significantly longer). I haven't played this since around when it was originally released, and only one stage boss gave me any real issues. I stuck with the standard path, so I did make it rather easy on myself. But I basically felt like popping it in, experiencing the game, and seeing the ending again since it had been such a long time since I last played it.
As for significant changes they made for this installment:
Rather than having a Difficulty Setting, they added some alternate paths to take within the Episodes which are quite a bit tougher.
The addition of a Berserk meter where your dragon can unleash a barrage of attacks when the meter is sufficiently charged up.
Depending on how well you do in each Episode, as well as which path you take, your dragon will become more powerful.
A save system (which, being how short it is, I really don't think is necessary).
A few things they added for this made for a much easier game than the first game. For your rider's handgun, instead of needing to push A, B, or C for every shot, this gun fires a burst of about 8 rounds in rapid succession, so your trigger finger (or thumb) is given a break. The Continue system where you would get more Credits based on how well you do in each Episode is replaced with an infinite continue system as well as the ability to save your progress (you reload at the beginning of whatever Episode you died and saved in). The Berserker meter, while it is a cool addition, also makes things much easier.