I enjoy the online tools as they fill in the blanks in my physical collection of books. I don't own everything, but there it all is in the builder anyway.
As for ease of character buidling, I think it depends on the game. If you are playing a straight Essentials game then the builder isn't really needed. Essentials specifically tried to go back to the days where you could choose a race and class, spend a couple of minutes making up some stats, make a choice or two, and be ready to go. On the whole, I think they succeeded quite nicely. I know there are people who are down on essentials because they find it limiting, but there is something nice about not needed a Ph.D and a spreadsheet to make the freaking character.
For classic 4th ed, which I greatly enjoy as well, the problem for me just going pen and paper is that there is so freaking much of it. Three PHBs, six power books, two books of just gear, more stuff in the Campaign settings, yet more stuff in the magazines, even yet more stuff scattered here and there in other products. You need to be some kind of char-ops cyber-warrior to keep it all in your head and you need a dumptruck to get it all to the game. I find the character builder to be a godsend for non-essentials dnd. Even trying to keep it simple it gets overwhelming. Lets say you want to build a Goliath fighter. Sounds simple, right. PHB1 for fighter, PHB 2 for Goliath, Martial Power 1 and 2 for more fighter choices. Whats the stats on a Fullblade again? Better Grab adventurer's Vault. You are thumbing through 5 hardbacks just for the basics, and what, you want me to pick a background? Where is the Campaign guide? Its just nuts.