There's always a very small bit of risk when doing a software update. Your phone is re-writing the software it operates off of, so if anything goes wrong, a factory reset is normally needed to get it back up and going. I've had it happen to my iPhone once, but forunately I had a recent back up, so was able to get the software update installed properly and then restore my content. I'd recommend making sure you have everything backed up before any software update.
All that said, what problems are you having? If you can still get to your home screen, apps, and settings, I'd recommend doing a backup and a factory reset, and see if that clears out anything that may have gone wrong during the update.