Shipping is in most cases free, so some items might take up to a month to arrive. As far as I know it's the best site for inexpensive 100% cotton and linen clothes and home textiles. Sizes for clothes can seem at first to be difficult if you're not familiar with Chinese sizes, but most of the sellers do provide detailed and accurate size guides and, if you read these carefully, you'll usually get things that fit. While you'll find a huge variety of good cheap stuff on Ali Express, and lots of bad cheap stuff too (I bought a cellphone which didn't have the same specs as the one advertised, but I got my money back), Ali Express also sells very good quality - and expensive - products.
I can't deny the fact that "Aliexpress" prices are really cheap, everything on their website is quite affordable, you can find everything on their website but based on my personal experience which was unfortunately unpleasant, I bought a ballet flat, a pair of sandals and a bag, I haven't received my ballet flats, the sandals quality wasn't good and they didn't match the photo on the website and finally the bag material was absolutely cheap and wasn't sewed well, I was very disappointed, not to mention that I waited almost 60 days to receive them. I'm definitely not going to buy from them again, but I must say that they refunded me my money and were very kind and cooperative. Wish you all a pleasant, easy shopping :)