I am mind boggled that people think 4e is a badly playtested game as evidence complain about the quantity of errata.
Without the errata 4e is a more robust & balanced game than any other I have come across. Part of the reason some of the errata is "needed" is because the maths is so tight in the first place (eg the maths feats like expertise). There are some "broken" aspects that got fixed like the infinite attacks from that Ranger power whose name escapes me but these stand out amongst the tuning up.
I will not defend skill challenges which still do not really work but the core skill system is much the same as any target based skill system in any RPG. It works as well as they do (ie better than "fixed" skill systems like CoC, Runequest or 1e thieves)
Errata (or updates as they call it as a bunch is of course evolution) shows they are working to make the game better
not that they did a shoddy job in the first place. If you do not like it that's fine - as I said the game will stand up much better than any other rules heavy system.
Meanwhile back at the topic. I am really unsure. I like crunch more than fluff but with the online stuff I find its a hard sell - especially things like Monster Vault which comes packaged with lots of stuff I do not want like maps & tokens, as well as stuff I do - like fluff. OK I like my crunch but I thought the Monster manuals were reallly light as I have no idea what half of those things even look like.
I thought the Neverwinter Campaign book was
probably excellent. I disagree with Kzach that it is not at least mainly a DM book & in case I end up playing there I have not read all of it