TUU is very good at doing what it claims and isn't that hard to navigate. You'll hear that you can get freeware programs that do the same thing (like ccleaner) but it isn't true. I have ccleaner also and I do use it occasionally (it has a nice drive wipe, freespace or total) but it's nowhere near as effective as Tune Up Utilities. It's not as in depth nor does it do as thorough of a job. There's a reason the one is free and the other is not.
To me, aside from keeping things nice and tidy, the best part about it is the program deactivator. Some of you gamers out there will find this useful if you're running short on RAM to feed your games because it'll let you turn off alot of hidden programs, most of which you probably never knew were running.
You might be surprised at just how much useless junk you've got running in the background that doesn't show up in your task manager. For me it freed up a considerable amount of RAM, definitely enough to make some of my more demanding games run better.
It will also configure your graphics settings so you can spend your resources on gaming and not powering fancy Windows desktop effects. These are notorious power suckers and letting TUU fix it can be a big help if you're running a lower end GPU.
Now, I don't use the Live Optimization function. I just don't. To me it seems to increase loading times and such, especially at start up. Maybe it's just me but I don't use it. You can try it though and if you don't like it turn it off. And something else I don't do is replace my Task Manager with TUU's Process Manager. To look at it it looks horrible and entirely too difficult to manage. The Windows Task Manager is much simpler and does the same thing.
EDIT: Don't use my review as a guarantee that this software is going to do squat for your computer. My review is my experience with it but that doesn't mean that it's going to do you any good at all. If it doesn't do you any good then you should feel secure that your computer is well-maintained and optimally configured and that you've got a very good software program to use in the future if that ever ceases to be the case. If you are unsure of it's usefulness, get the demo version and find out before you spend your money on software that you aren't sure you have any need of.