I have a 2013 e70 X5 5.0i xDrive pretty well equipped. It has given me no problems in 44k miles but it is still young.

The newer ones definitely have a better interface (iDrive) and screen, navigation, etc. It also feels a bit less substantial, some might say tinny.

For DIY it depends on how brave you are, and what tools and diagnostics you have. Mine is still under warranty so I don't touch it - at least not for another 6k miles. Not sure I ever will, given the low cost of indy service in my area.