Actually, I always avoided them because of the independent/small chain run off. However, I noticed that all the coffee shops I went to were always packed, and the obligatory Starbucks across the street were always empty. From what I understand Starbucks is suffering now because of overextension that just didn't work out. I am sure there were more than a few that forced smaller shops to close, but it didn't happen to the extent that was expected.
I also find the coffee they use to be inferior Robusta bean. For a while they switched to Arabica, but I think they are back to a blend of both species. It really does make a difference. I really don't find their drinks to be near anything you could get at a good cafe or make yourself.
However, since being here, I have started going. Caffe Nero's drinks are mediocre at best and they only offer the choice of skimmed and semi-skimmed for milk. IMO, Costa is pretty bad, worse than Caffe Nero's. I can't stomach that Costa instant crap (or at least it tastes like instant) that they serve at so many restaurants here. It's been hit or miss with smaller places. There aren't that many here that are truly coffee houses and not diners.
If you told me a year ago that I would eventually go to Starbucks at least once a week, I would have told you were dead wrong. Bad coffee and bad practices were my reasons for avoiding them for years. I still make better coffee at home, but we go to Starbucks now and then.