I have placed three orders with them. In total about USD$4000 of parts. LCSC is part of a huge group of buisness, ( SZLCSC, JLPCB etc ), and they are very legit. They are sort of the chinese mouser/digikey.. Freight was between $20 and $30.. one of the orders was 5kg. Parts are legit.. Mostly i was buying passives, though bought a reel of TI Switchers. Delivery was really quick, was with me in a few days from ordering, via DHL. Payment was via Paypal.
The web site is a dog. its really hard to use, compared to mouser/digikey. This carries through from the SZLCSC ( which is in chinese ) which is equally as bad.
you cnat' backorder things that are not in stock. THere is no information about how many parts are on a reel.. If you order say 3000 resistors dnt' expect them all to come on a single strip.
I have talked to them and they are looking to improve on things, but the proof will be in the pudding..
There are some real good savings to be made on some items, but not everything. You'll spend longer ordering that you will on DK/Mouser but you might also save a Lot of coins.