Nothing.
I only have 2 apps installed - WhatsApp and another one to track my work hours.
Other then that, I never did anything on the phone beside using it for browsing, but it began to lag a few weeks ago (not to mention I've had signal issues ever since I got it).
I'm not sure what I expected TBH. I had the first Galaxy and I don't think I've ever hated anything as much as I did that phone.
I didn't want to get close to Android again, especially not to the Galaxy line, but I had a chance to get the S3 for relatively cheap ($508 unlocked), and I went for it.
I don't think this is a bad phone, this has more to do with Android itself...