It is safe to buy form Aliexpress?
I bought so many things from AliExpress. Some products are good and some are bad. For instance, I ordered some octa-core TV Box and it turned out to be defective. To make it worse, the seller ignored my complains. So, I had no choice but to file for a dispute with some proofs and AliExpress honored my request to give me a partial refund. At the end, I only paid less than US $22 for an octa-core TV Box with 2 / 8 GB RAM / eMMC storage. Products I would try to avoid is any Lithium batteries, especially if ad the claims its capacity makes no sense, i.e. a Li-ION 18650 with 9,000 mAh, etc. This also goes to the same products sole on eBay. For such a Li-ION battery, I always look for some good deals from local stores, i.e. BestBuy, Home Depot, Office Depot, etc.
What I tried to say in the above is it is most important to fully understand about the ad. This way, you will really know what a product you are ordering and/or buying. A lot of sellers just put and/or copied everything from other ad and tries to sell you something that is not. In this case, AliExpress always comes to rescue with full and/or partial refund, pending on some proofs. When I did run into such an ad, I always contact the seller through PM. If the seller does not know what the issue is, I won't place my order and move on to other sellers.
Occasionally, I did run into a problem with some non received and/or delivered items, but AliExpress did a full refund on all of them.