I clicked "positive" but I guess my attitude can best be summed up as "cautiously pessimistic" in that it's possible that the damage to the brand may already have been done and the divided gaming community may not be easily healed.
The new team is impressive and I think Mike Mearls is a good choice to guide the new edition (his past 3E vs. 4E comments notwithstanding -- he was a guy who was defending the hard work that he and the other designers had done on 4E and did so in a very spirited fashion; I fully understand that).
The goals of this project are laudable, but as noted elsewhere they may simply be setting the bar too high. I can't see a single system that would unite fans of the Rules Cyclopedia with fans of 4E -- the differences just seem way too significant. The design team is free to surprise me, however and no one would be more delighted than me if I have to eat my words on the topic. Further, we have heard similar promises before only to have them crash on the rocks of corporate reality. Remember Gleemax? Remember all of the cool features that DDI was going to incorporate and how few of them actually appeared? Remember how the "new" OGL was going to be "more open than ever"?. Though those promises were made by previous regimes, WotC's record is a bit spotty, and it's hard to erase the memory of past disappointments.
That said, the approach that is being taken is refreshing, and I think extremely courageous. There's a tacit (and sometimes more than just tacit) admission of past errors and at least the implication that WotC has learned from its mistakes. There's a very bold and difficult goal -- to unite all previous editions into something that everyone can play.
It's a very, very ambitious goal, but in some ways I'd really prefer that they aim high and miss slightly rather than aim low and succeed (which as far as I'm concerned certainly sums up 4E). Also encouraging are the repeated assurances that WotC will really listen to gamers this time, and as evidence there's the much more open playtest period, rather than the secretive, years-long development process that led to 4E. There's also the implication that something like the OGL may return (though I'll believe it when I see it).
So I guess I'm wary based upon past performances, but optimistic based upon what I consider to be the refreshing new honesty that the design team is displaying. I am also encouraged by the team and its leader -- having worked personally with Mike Mearls in the past I know that he is a dedicated gamer and knows what he's doing.
I've signed up for the playtest and I'll definitely be giving them the feedback they want. Time will tell how successful they will be, but I am willing to give them every opportunity to save the brand and bring the hobby back to what it was. My only fear is that this may be too tall an order for even the most talented and dedicated team of designers to achieve. I nurture the hope that the designers will prove me wrong.