PC Gaming Microsoft Killing It
Game Development on PC is becoming increasingly difficult as compared to XBox.
Graphics - DX 9 on XP, DX 10 on Vista SP1, DX 11 on Vista SP2 and Windows 7, Nothing on Linux. Compare to OpenGL on everything. How Quake 2 still runs everywhere (except only XBox360 and that only due to MS not allowing OpenGL on that) having only just 2 renderers OpenGL and Software. How OpenGL lagged. Though ARB is still to blame also for that, and then game developers. It is bit more difficult to code for OpenGL than DirectX 10 but it can be done in bug free way (just see GPL code of Quake 3 and see how solidly it is protected checking everything and as a result, games based on Quake 3 are generally very bug free like Jedi Outcast).
Innovation - Majority of Multiplatform games have playthrough suited to only Controllers, so many Gears of Wars Clones.
Graphics Innovation - Majority are lowest common denominator of PS3, XBox360, PC. Except may be RAGE and Crysis 2.
Save Files - If one tries to synchronize PC and XBox360 development, PC version generally runs with profile save problems, Halo 2, UT 3, Gears of War (All PC editions). It is great detective work to find and restore saved games if you format your computer. How easy it is with Quake 2 and Half - Life 2 which directly save in Installed Folder and ask to leave them when installing, and many others which directly save in My Documents, both being elegant hassle free options.
Game Releases - It is Microsoft own released games that are delayed, badly ported or never released on PC. Gears of War(lots of problems), Halo 2(Very bad port and very delayed), Halo 3(maybe not come at all or probably after 5 years), Fable 2 and so on.