I've really heard mixed things. Obviously, if you are a style snob, you would be willing to drop 1000+ on a Samuelsohn or something, which not everyone can afford without some pretty strict budgeting.
I read a few men's style tumblrs, and while most of them are sort of against the quality/fit of Indochino, there are a few who seem to support the idea. This guy particularly:
http://suitsandboots.tumblr.com/search/indochino
Remember, this isn't a custom suit. It's a budget semi-M2M suit. When you buy a $1400 M2M Samuelsohn, you are getting some pretty top fabric, and at least a few measurement appointments with a tailor to make sure the fit is just about right. The suit is then made in Toronto, shipped to you, etc... The process takes about 3 months.
Indochino requires you to take your own measurements (go to a tailor and pay $20 to get it done for you), and then they make the suit in China or Thailand. It's a far more inaccurate procedure.