They're not bad for light use--they are after all meant to be low-cost computers. (i.e. getting a computer for the kids or Grandma, something to write a letter/check email, computer for those who aren't as savvy about computers, etc.)
My problems are that :
a.) Because it's rather inexpensive, major issues with hardware breaking down occur sooner, and
b.) I currently run two operating systems (plus three more via my qemu and SheepShaver emulators on Linux). The maintenance takes its toll on both the hardware and software (e.g. accelerated the wearing out of my CD drive by burning live CD's and distro isos for people)
What I might do is mull my options right now and save my dough. I just might see about pulling out the hard drive (junking this one) and replacing it with a better tower...