Our most recent THV stay was January 2013. Trouble with dishwasher - buttons on control panel goofed up. Problem solved with one phone call and maintenance brought an entire brand new dishwasher to replace the one with troublesome buttons - presumably easier to fix back in the "shop" and not in the villa.
One other weak spot we've noticed over time was the master bath shower control. Looks like maintenance addressed that over the past year or so with the new direction arrow sign in the shower to help people understand how the control valve works (direction to turn).
Overall, I think Treehouses are standing up well. We've stayed frequently since THV opened, and simply report the defects we notice - and they get fixed.