I picked it up the other day and think it's great.
I don't play shooters, so I can't give a in-depth review or compare it to other games of the genre, but I know a fun game when I play one.
The graphics are quite exceptional, I think.
DS may be lacking in visual prowess when compared to the PSP, but this is still a very pretty game.
As I said, I don't play shooters too often, so I'm not quite fit to judge the overall difficulty level of the game, but I had a decent challenge trying to get through it all.
And I'm sure as hell not going to be able to one credit it for a while.
I've read that this game had an extremely limited release, due to Majesco's financial problems, so if you have the chance to pick up multiple copies, you probably should and play the "let me sell this for a stupidily large amount of money on ebay game."