Topshop isn't an off-price brand, they started moving away from that strategy several years ago, and now see themselves as a fashion-led label with prices to match. I remember reading an interview with Philip Green (the owner) at the time in which he said something like "People aren't interested in price wars anymore- I don't see us competing with Primark and H&M and Zara for the lowest cost" So yes, anyone expecting "cheap fashion" from Topshop is going to be disappointed.
As for quality, it is hit and miss. Such a big company has a huge range of suppliers and manufacturers, so some items will be excellent and some stuff not so much. I recognize that label from my days working for a manufacturer who supplied Topshop, and it's for their nicer-quality stuff.
Like Dawn says, sizing is tts.
