It's got some very detailed sprite work and looks very nice. Yes, the game is a repetitive button masher, but really no more so than old-school beat'em-ups of the 8 and 16bit days. And if you intentionally try to use the various special moves as you play, it adds to the fun. It has a very old-school feel to it, which obviously I like. Control is pretty tight too. There are very few times where you have to fight the controls, though I would have preferred Thor's god powers to be activated by a button, rather than the touchscreen, but that's a minor quibble. I like how when you jump up in the air and you start attacking, he'll pretty much stay in mid-air as you lump on the enemies. I kinda wish there was more to the platforming....like maybe a few obstacles or puzzles as you move through the levels. It really would have broken up a lot of that "same-same-same" that the levels seem to have. I'm really glad they used Y for the main attack, the poor A button gets abused far too often in DS games. The A button is completely worn on my original DSlite (still can't find my tri-wing screwdrivers since we moved) and I've been using a backup DSlite. Luckily, the A button is only used for getting enemies off your back and knocking down pillars.
A few reviews talked about slowdown......I never really noticed any though. Everything moved fast and smooth as far as I could see, even with a lot of enemies on the screen at once. Working fine on CycloDS B.7.
It's a pretty short game though. I've only played it for about 2.5 hours last night and I'm already up to the beginning of chapter 5. I'll likely have it beat in less than 4 hours. I believe there are only 7 chapters with 3 stages per chapter, but I'm not 100% sure on that. Maybe some might find some replay value in getting all the runes and other unlockable content, though that's not something I tend to worry about myself.