Check out this thread: https://bitcointalk.org/index.php?topic=262052.580
I don't know. IMO a lot of the naysayers are just spreading FUD. I might be wrong about some of them, some of them might be genuinely concerned, but I don't feel like it is fair to treat HashFast any differently from any of the other unproven vaporware vendors. At least not until they have proven themselves untrustworthy. I just don't see enough evidence that would make me say that they are a scam.
You need to take everything that everyone says on these forums with a grain of salt. There are a lot of special interests at work. Not only manufacturer's special interest, but individual miners as well trying to spread FUD to keep difficulty as low as possible. I noticed one of the biggest naysayers was someone who has been endorsing the crap out of KNC, perhaps he just doesn't want people to order these machines and the difficulty to go up higher than he had planned, or perhaps he is being paid by KNC. You just never know...
Use your own mind and make your own decisions, but I don't see anything that would make HashFast a certain scam. Maybe their timeline is a little ambitious, but they are a bit cheaper than other offerings, allowing for a little cushion of delay time.
My two Satoshis.
Understood. I'll defer to the majority opinion.