I like to try new stores when I'm shopping around, and I always compare prices between at least a few different sites. For this kind of comparative shopping, PandaCheck is an awesome resource.
They write reviews on discount stores based in China, and occasionally post some pretty good coupons. The reviews are pretty generic, but their overviews of the shipping times and return policies are helpful when deciding whether to use a new site.
I mostly use PandaCheck to find new discount sites to try. I'm a competitive shopper, and I always like to get a better deal than my friends on electronics and stuff. PandaCheck is fantastic for this because they list a lot of obscure discount shops that don't always come up on Google Searches.
There's also a search function that scans the offers in different chinese shops. It's not the best search function ever, and it really only helps if you know exactly what you're looking for. But I have found it a nice resource when looking for Chinese-branded tech items (Xiaomi, Huawei, etc.).
One weird thing: they seem to have a lot of German users so a lot of the customer comments on stores are written in German and you can't translate them. There's also a Star-rating system on the different shop pages, so you can always see what users thought that way but it's annoying that you can't translate the comments.