Site is quite legit and is quite popular. It's used by a lot of ebay type sellers in search of small bulk loads to break down for sale.
Things you have to watch out for include:
1. The site is an auction type format with independent suppliers selling their stock, therefore as with most sites like this you will get good traders and you will get ones that are trying to auction off complete garbage.
Do your research on any seller you are thinking about bidding with.
2. Watch our for the shipping prices, liquidation.com have some of the most extreme shipping prices around and they can burn your deal quick if you haven't already factored them in.