I'm up to the 5th level (playing solo) and I totally agree with all of the positive impressions here.
The level design has been fantastic so far, and I love the challenges and incentive for replay.
The game looks great; one of the best-looking XBLA/PSN games to date. There's some very nice lighting, and many little details (falling dust and debris, tapestries that ignite and burn if exposed to flames, destructible props, etc.) that many full-blown retail games lack. The isometric view allows for a sense of scale that's different than a standard Tomb Raider game, but still very effective. Lara's animation is excellent as well - her flailing leap looks much more natural than the equivalent animation in Uncharted 2.
I'm really liking this trend of "big small games" like Lara Croft, Shadow Complex, etc. These kinds of games would never see the light of day as retail products, but the downloadable space seems to have become the perfect home for these kinds of games.
I hope this game sells well enough for EA to look at it and think, "an isometric action/adventure game sold well... hm... Crusader: No Remorse..."