Dead Rising 3 is going to be an Xbox One exclusive. Also, Insomniac Games's first nex-gen release, Sunset Overdrive, is going to be an Xbox One exclusive. I mention this last one because Insomniac Games are known for their Sony-exclusive franchises.
Forza 5
Halo 5
Sunset Overdrive
Ryse
Quantum Break
Titanfall
Crimson Dragon
Dead Rising 3
Below
D4
Killer Instinct
Project Spark
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Kinect Sports Rivals
Zumba Party Fitness
Untitled game from Black Tusk studios
I believe that's all of the Xbox One ONLY games, there are others that are Xbox exclusive but are also coming to the 360.
Neither console is backwards compatible, the PS4 isn't because the Cell was a piece of shit, and they've ditched it, emulating it would be too CPU intensive. 360 games would run like ass on the XB1 so that's also out - some games may be covered by your subscription though as downloadable games but discs won't run.
AFAIK the Xbox live subscriptions cost the same as they always have, however it is likely that both services will offer exactly the same though, old games for free and unified friends lists and the likes. As well as the new 'share' feature, although at least Microsoft don't have a fucking button dedicated to it.
In other news how amazing was The Last of Us.
If you have a PS3 and haven't played it yet you should follow these simple steps.
Stick a pencil up each nostril.
Slam ends of pencil on a desk/counter top*
If you survive, go buy the last of us.
*do not actually do this, it has a decent chance of causing significant if not fatal harm