Can you build beautiful sites with Twitter Bootstrap? Hell yes
As a single founder/developer, I'm a huge fan of bootstrap. I can handle making the frontend and backend of my site, but I can't necessarily make it pretty - especially because I honestly have kind of tacky taste. With bootstrap, I can get my site to atleast a passable level of prettiness, and not spend all my time tweaking CSS (which can take so damn long).The main issue I'm seeing with bootstrap use now is lack of customization - everyone using the default colors and styles - so that when you load one of those sites, we think, "a-ha! bootstrap". It probably takes some of the magic out of a site's novelty for developers with that reaction. I'm not sure it affects non-techie consumers -- maybe it's bad if they can't visually distinguish your site, but otherwise, I wonder if they actually notice.I spent a bit of time customizing the Bootstrap look & feel for my own site - turning that somber black bar into a bright and sunny bar: http://www.everyday.io/
(Screenshot of logged in screen here: http://dl.dropbox.com/u/10998095/Screenshots/bootstraplogged...)
I also use bootstrap for the mobile (Phonegap) version of my site, and it works surprisingly well (http://www.everyday.im/learning/switching-jquerymob-bootstra...).Thanks, bootstrap team!