I have used SolidWorks and Inventor quite a lot. While my experience with SW was a pleasant one, i never want to use Inventor again.
Inventor seem like it was built off of a 2D program (which it probably is). The most annoying thing about it is that you need to activate a special function just to orbit around your part. When sketching, you can't exactly use axes or anything. Any drawing you do is just floating in space. Also, making the features on one part depend on the features of another (in an assembly, of course) is nigh impossible. You have to go into that 'adaptive features' business, which works only half the time, and then only if you spend half an hour figuring out what constraints you need to create. And let's not even begin talking about how backwards sketching is in Inventor. I've had simple sketches that took me 7-10 minutes to do in Inventor, and 2-3 minutes in SW or CATIA.
SW, on the other hand, doesn't suffer from those impediments. All sketches have a axis system, relative to which you can define constraints, sketching couldn't be any easier. You can edit parts easily in assemblies, and define them based on other parts in the assembly. Also, you can define various configurations for parts. Overall, much easier to use.
Everything I've said is a personal opinion. I work about twice as fast in SW or CATIA than in Inventor. I wouldn't recommend Inventor to anyone, especially beginners. If you want to draw 2D, there's nothing better than AutoCAD, but for 3D... I wouldn't go for Inventor... It's just too backwards...