I had a hard time with 3e in the beginning.
I'm having a similiarly hard time with 4e.
I ran, with few problems mind you, two sessions of the Keep.
I was highly disappointed in it as a first adventure for a variety of reasons ranging from price point, quality of paper, unimaginative foes, plot, lack of details on characters, etc... etc... etc...
The system looks very player oriented with lots of crunchy bits and looks to be very DM friendly with monsters that don't follow the same rules as the players.
The DDI is, at this point, a failure. I'm (still) a little bitter about the cancellation of print Dungeon and Dragon magazine and WoTC complete inability to do innovative things with their online replacements. I'm a little disappointed in their ability to do things that are standard from other publishers like have a log on that doesn't log you off. Like updating their products with errata and reposting it. Like having multiple print options. Landscape is a good novice step in that arena but it's far from the best they can do.
In terms of 3rd party support, fail again. I'm not a publisher so it doesn't effect me in one area. In another though... I've played in the Scarred Lands. I've enjoyed the Slayer's Guides. I've enjoyed the birth of adventure/settings like Freeport and Bluffside. Things that would not be possible without OGL.
I won't say their marketing campaign has failed, especially since the print run has already gone out, but it has completely failed to move me. If this wasn't D&D, I think it would've fallen hard and falt on it's face.
The minis in Dungeons of Dread are also a mess. It's like they went back to Harbringer standards in terms of the quality of many of the sculpts. The next set doesn't look to have a lot more promise with a lot of solid single color figures.
I'm also one of those people who never felt shackled by the enormous depth of the Forgotten Realms but found that it amde DMing the setting far easier as it was "alive". The changes to the setting are a kick in the stomach. If I run FR in 4e, it will be with the previous timeline. I'm glad that Eberron fans won't have to endure such a shift.
In some cases, people will argue that WoTC had to focus on 4th ed. And if this was a last minute announcement, I'd agree. But they've known about it for a long, long, long time. Far before any normal gamer knew about it, WoTC knew about it. Claiming that they couldn't support DDI, OGL, etc... in a timely fashion because of the 4e push is a sign of bad management.
I work in a factory. If we have a huge order coming down the line and fail to get in proper fill rates, it could cost several people their jobs. They can't go, "well, we were busy with the day to day minuta."
For now, as I'm still getting used to it, it's not D&D, it's 4e. I'm an active player in a Savage Tide campaign right now. After that's over I'm running the Freeport Trilogy (modified 3e) and after that, some Goodman Games adventures set in that campaign setting(also 3e). In addition, one of my friends wants to run some more of his on again off again Mutants & Masterminds as he highly enjoyed the last several books from them. The guy running Savage Tide wants to run some Hero but is waiting for the new edition before putting the "final" touches on his campaign.
Another one of my friends is dying to see how Pathfinder comes out. He's really hoping that Paizo can salvage his $2k investment in 3rd ed.
So for me, 4e is just another engine, it's just another game. I'll play it and hopefully, like 3e, as I learn more and play more, and WoTC becomes better at this online elmenet that THEY made crucial, will come to call it D&D and not 4e.