KensingtonLabs purchased mining contracts from cloudhashing back in May of 2013 that were suppose to start in June, then they didn't start until July, and when it started it was only at 25% of full capacity or some crap like that. We spent a total of 3.5 BTC (because back then BTC was the only way to pay) and at this point have only earned back .4 BTC. It's pretty safe to assume that by the time our contracts are up we will have nowhere near close to the 3.5 BTC initially invested.
It was our own fault, we fell for the flashy advertising on the site. They basically said 1BTC would earn 5BTC over the year contract. We should have known better, but we fell for it. We got scammed and would have been better off holding our BTC.
Now...if you are paying with credit card (which is currently an option) you will get a decent service. It's a little bit pricey, but you ultimately will see ROI. Whatever you do though DO NOT EVER BUY BITCOIN MINING CONTRACTS WITH BITCOIN, YOU WILL NEVER GET BACK AS MUCH BITCOIN AS WHAT YOU PUT IN. This company is notorious for delays, and spending all their funds on advertising. They also recently added a customer support team to deal with pissed off early customers like us who constantly e-mail them saying "what the fuck guys...what the fuck"
So in short, cloudhashing is not technically a scam, but anyone thinking they are going to spend bitcoin to make bitcoin should just hold instead.