Well, I'm new around here, and I've been to our only Teavana several times, so I thought I'd chime in. Just consider my lack of years of dedication on the subject of tea.
Most of the time I visit Teavana, they seem to be pretty nice to me. But I live in a state that's creepily hospitable, so maybe that has something to do with it. Only once have I experienced over-pour, and only never have they pushed me into buying anything I seemingly didn't want or need.
That aside, as far as their tea quality goes, I think I should preface my opinion on the fact that I really only drink non-tea infusions. I have for years, and I doubt I'll start anytime soon. And while I haven't tried everything in the store by any means (our store is so small that it doesn't have a tea bar), the opinion on the half dozen or so blends I have tried are hit or miss.
And blends are all I can really relate to, as I don't drink real tea.
Their rooibos are hit or miss. The batch of their honeybush blend I brewed was horribly overpowered by the vanilla. I do enjoy the non-Tea Chai blends I've tried, though. Those were somewhat tasty.
Ignoring the pushy sales people issue, I think I fall pretty much with the popular opinion on these boards that while some of blends can be tasty, they are often times overpriced for what you get.