We are starting to use Chromium Embedded for all of our in-game UIs, after going through Flash and (for a brief period) CEGUI. No major regrets here. In fact, we like HTML so much that we are considering moving our game tools (level editors, etc) to HTML as well, ala Insomniac [1].
[1] http://www.insomniacgames.com/new-generation-of-insomniacgam...