The Nitrous guys have been extremely responsive, fixing a bunch of bugs that were causing me problems (like awaken-from-sleep, problems with $COLUMNS on a retina display). Their terminal emulator is great; it even has mouse support (although it seems to be off by 1 diagonal column -- looking forward to seeing that fixed soon).
One extremely important point: by default today, ChromeOS discards tabs when it runs low on memory. This experience was sufficiently problematic for me that I almost gave up on the entire thing, until I learned about http://gigaom.com/2013/04/05/running-out-of-memory-on-a-chro.... tl;dr Google is experimenting with zRAM (https://en.wikipedia.org/wiki/ZRam), which will eventually be on by default, and you can trivially enable it right now. Do it.