The iOS 7 upgrade was pretty major, not just in looks but a lot of the backend was updated.
It's not unusual for the first few versions to be less stable than older versions. This should be ironed out as minor bug fixe updates get rolled out. I'd expect the first real bug update within the next month, but that's pure speculation. The previous two (very minor) updates were rushed out to fix security issues, rather than being major bug squashers.
So, yes, I've noticed a few more crashes, minor problems, and one or two just plain odd moments, but not enough to make a huge difference. At least not for me.