Imaro
Legend
I know anecdotal evidence isn't, but I play in two 4e games (and no Pathfinder games), and have used Essentials material in both of them. In one, all the characters except one use an Essentials build. In the other, one character occasionally uses an Essentials build.
It's probably achieved a deeper penetration with my groups than, say, Martial Power II has. And the players have bought books! And not DDI accounts!
I'm pretty on-record as being an Essentials fan, however. I think the problem came in when some vocal 4e fans decided things like the ADEU power structure was sacrosanct across all classes in all cases (except psionics?), for reasons I still don't clearly understand. Essentials wasn't going to sell to current 4e Trufans very much. And then it was followed with months of little to no product, and people started freaking out...
And, of course, now Mearls's articles aren't putting anyone's fears at ease.
I will say this, I too was an Essentials fan (I even kept my Essentials books when I gave away the rest of my 4e books to my brother)... however I did get a little ticked off at the way the magic item rarity system was never really completed, and that there were no multi-classsing rules (now we have them but they are incomplete and not in the actual books), as well as the way it seemed they purposefully left stuff out (Fall and Winter sentinel druids... I'm talking about you ) in order to supplement it in Dragon (which would have been fine but marketing led me to believe that Essentials was going to be a stand alone evergreen product and some/much of that material to round it out has been glacially slow in coming (Weapon support for the Slayer other than staff).
I think those were some of my biggest beefs with Essentials, it felt unfinished and honestly as time progressed the way the rounding out of the material was handled by WotC soured me on it.