I would say this is a business that is going through some major growing pains and seems a bit disjointed if you are looking at them as an avenue to make extra money selling your clothes. The only thing I now will send into thred up is if i have a bag of NEW with tags clothing, otherwise. I will NOT send in a thing. I use another company for that type of thing and they are more than fair.
As for buying, I like buying for the most part. Some prices have gone up significantly during their "growing pains" and for those reasons I have stopped buying as much as I once did, as I can find better deals at other places. Shipping to you is not bad at all. Time to process your bags I would rate as average, due to their expansion. Search function is nice. Customer service seems to be O. K.
As a whole I do not use the clean out bag function as I get better pricing and selection elsewhere. As a buyer, I am still buying a few things, but prices have gone up significantly, some to the point where I can buy the same item NEW other places for the same or lower price.
Hopefully they revise their selling model and go back to what worked for them before all of this major expansion happened.