I bought the 50mm f1.8 not long after I got my camera, and got the 24-70mm f2.8 a good while later.
Initially I was really pleased with the 50mm, but using the 2.8 zoom set to 50mm I preferred the results. OK, it's not as fast, but that didn't cause me any issues.
Like a lot of people I think I enjoyed the novelty of the f1.8 because finally I could take a photo with a blurred background! But if you look at the quality of the blur it's not very nice (5 blades, pentagons..) In the end I just wasn't using it, so gave it to a friend.
I still wanted a prime though, for low light and simple '1 lens' days out, so I was going to go for a 50mm f1.4, simply for the better build quality & smoother OOF areas.
If you can get a 2nd hand one, it's worth a play with. Depends what you need it for.
via TP Forums for iPhone