Almost nothing, but sometimes I am unable to use TeamViewer when there are unknown networking issue, probably due to company's firewall protection. I launch TeamViewer and leave it on before I leave office, but lots of times I can't get access my laptop in the office via TeamViewer when I got home. That is the only issue I have with TeamViewer.
I used LogMeIn before, 5 years ago. When I first saw TeamViewer, I was pretty impressed by the intuitive interface, ease of control, simple log in/register process. The best part is that it supports file transfer. I believe there must be lots more awesome features, but I am pretty satisfied with what I have right now. Will definitely recommend TeamViewer to people who have the same need as me.