A computer is a computer. It isn't perfect - you will have problems no matter what.
If you are just going to use it for surfing the internet, email, and word documents & such, then just buy a Dell and save the hassle.
If you are doing anything intensive, build your own. If you do everything correctly and take care of the computer, you won't experience many problems.
Again, no computer will be perfect, they will all have problems. But the thought is that if you build, you get the exact parts you want, which are much higher quality than most pre-configured PC's. Plus you get to see how all the parts work to get a better understanding of how it works, and you get a sense of pride in building such a powerful piece of equipment.
We can help you pick the best parts if you want to build.