Disclaimer: I haven't personally used it yet, I'm basing my opinions of the various screencast videos I've seen of it:
Lack of a traditional Index tool kills it for me. I use this feature multiple times every day. I suppose if Search were better implemented (with live as-you-type results) then it might pass as a substitute.
I'm not entirely convinced moving it into the browser with no supporting chrome is a good idea. I understand the new help system is based off a lightweight webserver, so surely they could just reuse Document Explorer but get it to use the webserver rather
than the compiled-help files and retain the TOC, Index, and Help Favorites?
Similar to the lack of the index, the new TOC does not sit well with me. I like having the "browseable" TOC that lets me just browse around the help content and see related things. I'll criticise earlier versions of DocEx for buring the "Sync TOC" button
(I always move it next to the Forward button and make it bigger).
In conclusion, I feel the new Help System is only an improvement for F1 help and not much else: if you know exactly what you're looking for you can't use the Index, but you can't browse around if you don't know what you're looking for either, as the TOC
lacks the same usability as earlier versions.
I might just go ahead and build my own MSDN browser chrome actually...
oh, you dont have to, h3viewer comes to the rescue