I agree with hailstop that the character builder removing feats you don't qualify for can be a problem when building a character, since you don't see the tradeoff. Sometimes it's useful to look through the books while building a character.
And, of course, the DDI cannot replace fluff heavy books such as the Campaign Settings and Campaign Player's Guides.
I'm not sure I said that, but what I did say was that CB doesn't give all the needed details on a feat. I think the text is whatever the summary text is in the table...not what's actually listed in the details.