I've been a dabbling photographer for a long time, trying to get a bit more serious, lately.
Because of that, I watied a long time to get a ball head for my camera tripod. I have a nice tripod (not a great one, I've read in several places, but a good one) which came with the standard pan/tilt head. That's the only kind of head I've ever used, plus I didn't realize the head could be replaced, so I never gave it a lot of thought. (Mostly of the, "well, when I'm thinking about replacing this one, that's what I'll do. But that won't be anytime soon" variety.)
But recently I read something that led me to think about the head being replaceable, so I pulled the tripod out and started monkeying with it until I figured out how to take the head off. And it's a good thing I did, because I found that the tripod is better than I thought, in that it can go down to only a few inches off the ground. I don't expect to use that feature a lot, but I'm sure there will be times.
But now that I knew I could put a ball head on it, I went out and got the Really Right Stuff BH-55. It's major overkill for my current needs (heck, the mid-size ball head might be overkill right this moment), but I didn't want to find myself wanting the bigger model a year down the road.
One good thing about that is that the knobs are quite oversized, so they're very easy to manipulate.
But the really big difference is just using a ball head. It's amazing how much easier it is to set up than the pan/tilt head. Not only does it take mere seconds to level, but getting the camera on and off with a twist and slide is so-o-o much easier than having to (un)screw it.
I suspect it's also more tightly held than before, but unfortunately I don't have any good way to measure that. But it should help make better pictures, which is definitely the priority.
So if you're thinking about getting a ball head, but can't decide: do it. You won't regret it. Most likely you'll only regret not doing it sooner.