I've had my Bushmaster ORC for about 5 years, and have in the neighborhood of 10K rounds thru it. I've had no issues at all. Clean it after shooting and every so often, if I dont make it to the range for a few months. My only regret is that I wasn't able to buy it sooner.
The only mods I've put on is a Nikon ProStaff 3-9x40 scope, a Magpul Trigger guard (since the flat one it came with was sharp and didnt like my trigger finger) and every now and again I'll swap the Bumpfire stock on to it, and have some fun with targets at the range.
Pick up some extra mags, and have a great time. I've used both aluminum and polymer mags. I prefer the metal, but the gun doesn't seem to care.