Amazingly enough, in this world of high tech e-commerce, you can click your mouse button to buy the product, but getting a rebate is still the commerce of yesteryear. This is intentional, of course. This is how Cyberrebates ekes out its profits. A certain number of folks are going to think it's not worth the hassle, or they're going to forget and let the rebate deadline slip by, and then they're simply stuck with no rebate on an item they paid far more for than it was worth. These poor saps are the ones making it possible for you and I to get our orders for free.
Rebates are slow.
This is not really a problem specific to Cyberrebates per se, because it seems to me that all rebate processes take forever. Cyberrebate only took 3. So, as far as complaints go, this is the least of them. Be aware of the hoops that they will make you jump through. Follow the instructions, and above all do not let the rebate deadline pass.