The hotbed was bent and the center was higher than other 4 corners. It was too severe to adjust by leveling screws. Even I loosen the screws and removed it, the center was still much high. I ruined several printing and asked for an exchange but refused. The seller sent me a new heat bead but it didn't include the original magnetic pad adhered to the heat bed, so I couldn't use it. The seller asked me to fix it by myself. Totally disappointed.
The seller refused to pay return shipment fee.
Last weekend I could print sample (a robot) with this printer. It is quite easy to set up before first printing, and the printer itself is quite sturdy and the quality is so good if you consider its price. I had an event with shipment - some part was damaged, but the seller did his best to replace the broken part. My son is quite happy with his first output. I definitely recommend this for your first 3D printer.