I never had any problems. The call reception isn't as good as my current phone, but was always good enough for me. I didn't have too many dropped calls, but be aware that they use Sprint's network (and are in fact owned by them) so see how Sprint customers get by in your area.
I only used it a few times with my crappy little phone, but I found it to be pretty slow and sucked down plenty of my cash for not much benefit. I'd say this is the biggest weakness I found, but other handsets might be much better than mine.
Why do Aerospace Engineering students have to turn things in on time?