I also use Final Cut Pro X as my main editor and the main reason I use Motion now is because it integrates much better with other Apple software than After Effects integrates with other Adobe software. read more
I have both, although I have to admit that despite owning Motion for over 5 years, I've never actually used it. read more
I actually started animating for the first time in Apple Motion, and I agree that the learning curve isn't quite as steep as After Effects (although that was Motion 2.0 and 3.0, and now they're at version 5.0). Once I mastered Motion and dove into After Effects, I haven't looked back. read more