My own experiences with them have been good, but both times were super low priced item problems.
I purchased one of the Hyper 212 fans that didn't have one of the mount kits, so they sent one out for me. Quite a few years before I had purchased one of the Elite mesh cases and the little fan on the side had a cut wire so they shipped me out a new fan. They were both mostly easy to deal with. I recall having to do a lot of paperwork/footwork in relation to the missing mount for the cooler, but it has been a while now.