you can check the performance in smallnetbuilder
I would say it's not that bad for it's price, but it also means its performance is reflected in the pricing.
C/P is not better the synology or qnap, just depends on what you look for.
you can also check thecus for the really budget ones. Less then 3K you can get a 4 bay with single-core atom nas. Didnt really own any of them but from spec it's more C/P wise