I've played through the previous game and iX1. They were pretty okay but I don't like this one.
For the basics: the challenge of playing as Gunvolt is to tag multiple enemies in such a way as to get simultaneous kills. Most of your score comes from this. But there isn't that much to it, enemies are basic and the challenge is more just remembering the level layouts. It feels in reality like a more roundabout, abstracted version of going for a good run in a Megaman Zero game, without any of the immediacy or good level design that those games (mostly) had.
Copen is about staying aerial and dashing into enemies, which is fun on a basic level but if you intend to play for score it's probably even more tedious than Gunvolt since it's 100% about memorising the level layout. After all, he clears multiple screens with a single dash, you can't see where you're going so you have to memorise that crap. The level design is also worse here than in iX, and the bosses are way worse.
Boss fights in Gunvolt 2 ♥♥♥♥♥♥♥ blow. GV1 and Luminous Avenger iX were alright in this regard, but there's so much chaotic, messy ♥♥♥♥ going on in GV2. Gunvolt himself can at least see what is going on, but Copen is going to have to be "Copen" with not seeing about 1/3 of the screen any time he wants to do damage. And there are so many weird attacks where figuring out what the game expects is going to involve a lot of trial-and-error. The silver lining is that you can just brute-force the boss fights for the most part using prevasion, but if you want score then you probably want to learn the bosses at least a little... the difference between GV1 and 2 is that in the former I learned the bosses in the course of playing the game normally, and in 2 I think you'd have to read a guide or else devote some serious time into learning and practicing exactly how to fight each one.
I don't expect a good story from a game like this, but if they're going to waste my time then it's nice if there is at least something semi-coherent going on. The opening is fairly epic and implies the presence of a story, but there's not much after that... you have another generic messiah-complex-style baddie to fight (remember MMZ1? Remember GV1?) and then it's the end (oh! But you have to play the final chapter four times to get each ending! Epic!!!!!)
I really wanted to like this, and the Gunvolt series in general. Inti Creates are usually a good time. But I don't think these are very good and especially GV2 is just bad...