Oh, I have nothing negative to say about the guy as a seller...I've never bought from him...and I have heard that he is very flexible in regards to returns/exchanges, etc. I just know he's picking up his supply from China and the majority of it is inferior to other products out there. Will it work? I'd guess the majority of it will... but just like Harbor Freight, when you go in, do so with the understanding you're purchasing product that likely is (A) a ripoff of a legitimate product and/or (B) likely an inferior product to others out there... but the benefit is that they're offering it up at a much reduced price.
Like Harbor Freight, there are certain applications a "cheaper" "less expensive" tool/part comes in handy... but there are times that a "real" tool/part (ie: Craftsman/SnapOn/etc) is a better bet.