I've only read bad things about Negri, unless they changed a bit since.
Link to read
It seems the owner/CS is very defensive and won't admit to any mistakes. They will overcharge you and then if you e-mail to them complaining he will say "we do not need your business if you are threatening us." They won't refund you anything.
There are some positive reviews, but from the bad ones it seems if a problem did happen they wouldn't help you. I would prefer Amazon over Negri.
I have never used Negri personally.
Just keep in mind that the people who had a bad experience are the most likely to spout off in reviews and tell everyone about it. Not saying that Negri hasn't ever made a bad call with a customer, but the cases with these things usual stem from people not understanding what they're getting into buying an unlocked phone, and they expect the same experience as going into a carrier store where the sales reps wet themselves to make a sale... And then they're disappointed when the warranty doesn't work out or they don't get to take back 5 devices for "flaws" and get replacements for free.