So I got the game - I've played a couple hours of the campaign mode.
The new units are interesting - I really like the bike - it's essentially a super-mobile infantry unit. It makes conquering larger maps a lot easier. The story isn't as cheesy as Advance Wars: DS, but it's just as irrelevant.
They changed the controls a bit and I dislike it. I typically play the game with a stylus-only, and a lot of things I used to do in the previous version I can't do in this - for example, I liked to select a unit, select a path and then see the options available to me and the % of damage it was likely to do if it was attacking. On the other version, clicking anywhere on the screen cancels the action, in this version, you need to hit B or click on the "cancel" box, which is annoying.
I'm not a big fan of the new graphics, either - in particular the new landscapes and maps.
Those small things aside, it's still the best portable turn-based strategy game around and it will definitely replace Advance Wars: DS from here on out.
Edit: : DS were smileys...