It's actually quite close to the Dreamcast version, with the exception of it being in 2D and the ability to halt and resume the game at any time, if you need to play in short spurts. It's very convenient with the save or resume features.
As for the game. If you liked Evolution Dreamcast, you'll like the pocket version just as much if not more (because it's conveniently portable). They really crammed the whole thing in there, music, graphics, the translation is very well done considering it's the NGPC.
It still has the issue of your high-level stuff being a tad overpowered, but they didn't cut anything out. It's a very long game, and one of the longer RPGs to hit a pocket system. Let's just say, it's one of those games that makes you glad the NGPC has that 40 hour battery life. Just makes you proud to own a system that can play one of these things without changing batteries.
One thing I'll also have to say about Evolution, is that it came at a very stale time for RPGs on any portable system. The Gameboys weren't exactly bringing in RPGs that were anything to shout about. Mostly RPGs that were hacked down to easily fit on a Gameboy color cart. So they were sort of like mini-RPGs with limited combat and content. (which helped because those systems don't exactly have great battery life) This was one of the only portable RPGs released, that was the full length of a console RPG and with the same amount of content.