There is no risk whatsoever buying from JOOM. Aslo, if you pay with PAYPAL you have their protection as well - but this has never been necessary.
I think all the negative reviews come from disgruntled resellers who want to discredit Joom.
Have ordered dozens of items from them. On 3 occasions I wasn't happy with the quality - got refunded immediately, without even having to send back the items.