My Tab P12 works well. I use it at school 6 hours/day and the battery struggles to keep up on some days, but it does all the stuff I need it to. It's got a good processor, nice big screen.
My device gets 4 stars because it came with a little adhesive sticking out near one section of the screen (clearly the screen had been replaced before the sale, and it wasn't cleaned up all the way). no scratches on it, though. I trust backmarket to get me good equipment.