I guess we should applaud Remedy for at least trying. When it's not breaking up, it shows extremely interesting visuals. The character models also received a lot of love. If the PC version has a stable, clean image then their methods are redeemed IMO!
It's definitely up there when it comes to complexity, real-time GI isn't easy (to get an idea you can read on this presentation by Q-Games: http://fumufumu.q-games.com/archives/Cascaded_Voxel_Cone_Tracing_final.pdf). My main gripe with the game is that it's very reliant on screen space techniques which break very easily.