I don't have a RealDoe, but I have a Share, which is pretty similar. I love it. It's pretty tricky to insert, especially if you're not 'warmed up' beforehand. One major thing, and I can't speak for any possible difference in stiffness between the RealDoe and the Share, is that I can't walk around much with the Share in. It's kind of floppy, and its own weight tends to pull it out of I move around too much.
I chose the Share over the RealDoe because the design looked... more streamlined, I guess? And I didn't care how realistic it was. It's just prettier to me, and I like having a pretty dick.
If you have any more questions, I'd be happy to answer as best I can.