When Microsoft first released XNA I was sceptical. At the time I was playing around with C++ and DirectX, feeling cool but slightly unmanaged. Not really making any progress at all. What forced me into XNA was XBOX and WP7 development. Loved it from the first Hello World.
So why do I like it?
1) First of, it is managed! Memory management problems gone. Well almost gone, Compact Framework and the 1-gen GC introduced a new type of memory management problem instead. But that's hopefully history in WP8.
2) It is simplified but yet extremly powerful. You must love the content pipeline and the very well defined life cycle that puts your right in the correct place of complexity. You still have to roll up your own game engine but all the extra low level details are taken care of for you.
3) It's now cross platform through MonoGame!
Why do you like XNA/MonoGame?