I have had a pair for about two years. Raced on them in crits and road races and I wasn't the only one. They have been fine. They are a fairly generic rim, mine had Novatech hubs with uprated sks bearings and Sapim spokes. I have replaced the cartridge bearings after about 10000 miles which I would expect with any wheelset and the rims have stayed true throughout.
I did have an issue a couple of months ago where the rear rim had developed some minor cracks around some of the nipple holes. I sent Superstar an email to see if I could buy a replacement rim. I had done about 12000 miles on them so fully expected to pay for a rim and get it re-laced at the lbs. The customer service team came straight back saying they didn't have the 30mm rim in stock anymore, but would I be ok with them re-lacing the hub to a 38mm rim under warranty as the wheels weren't quite two years old, so very impressed with the customer service.
Overall I am very happy with them. They are light, durable, serviceable and good value. You don't want to be stuffing a £1k pair of Zipps in a crit.