I don't think it's true, to be honest. "Not quite there" is a face-saving way of saying "I really like this". I've never used ICS, but Gingerbread was "not quite there". Windows Phone 7 was "not quite there". As of WP7.5, it's there. The only (only) thing missing is the huge app catalog, and Mango is ahead of the competition on many fronts.

With a self proclaimed iOS lover, "not quite there" is code for "I like this but I can't like it more than my own choice". It's a defensive maneuver.