Rpg.net, with a slightly more nuanced poll, has 4E approval at 61%. Another 9% are on the fence with 16% not caring or undecided. Enworld has a much larger sample, but only a simple up or down poll on whether you like it. 75% have voted positively. There are older polls out there with more negative results, from rpgworld and Paizo, but it seems that the newer polls are more positive, and I think the Wizard's Presents books have had a strong impact on this. That alone should tell you that these are not your average player; these folks tend to be more plugged in. It sounds to me that if you can get 70%+ of the alpha players excited about your product, you probably have a success on your hands.
One of the detractors commented that he was shocked that the two polls were tracking so positively when so much energy was directed at criticizing the 4E changes. The response:
people who like what they're seeing are less likely to spend five hundred posts convincing everyone else of the same thing...
Those who don't like it tend to focus on practical consideration versus quality of the content. They don't want to make the investment, they feel it's too soon, they don't want to commit to the reading, or they're perfectly happy with that they have now. Add into the mix the knowledge that within a couple years they'll be forced to buy it, and you can see where the detractors get a lot of their animosity. In the past, versions of the game have acquired a strong early foothold and dominate game groups and convention games in a very short time.