They are legit and I have never heard of them straight up ripping someone off but their customer service sucks and they dont give a shit about their small customers.
I have no doubts they are legit, but they suck with customer service and not only with the small ones. My friend has a huge mining "farm" and he had issues with every order he made like paid products showing unpaid (actually he had to send some emails to change this), delay with the delivery and wrong products delivered. You don't have idea how hard was to change this product, we had to contact the chinese support.
From the past 3 months there is many complaints on bitmain site orders. You will be able to make the legit orders with them but since they are receiving huge number of orders directly they are making delay on production and delivery bery slow.
If you are looking outside to purchase the antminer series hardwares you will be able get it on time but the price will be little more than you find in the bitmain site. Check with eBay resellers.