The tab bar becomes almost unusable when you have a lot of files open, depending on how wide your window is. I'm hoping to see this fixed in version 3. This is my only gripe with Sublime, but it's bad enough of a problem for me that I might stop using Sublime.
I think Sublime should do what Eclipse does... it shows only a maximum number of tabs that will be legible and usable given the space available. If more open files exist than the number of tabs that can fit, it puts the additional tabs in a menu on the right side of the tab bar. Files that are inactive (not been edited in a while) end up in the menu, but will return to the tab bar when you select them. Not only is this a good UI, but it's also something that A LOT of developers already know from using Eclipse.
Some might say that your open files are in the left sidebar, so use that instead. The problem with that is that my projects are very large and my scroll position in the left column is important, so scrolling to the top to get my open files is not convenient. I think A better UI would be to put the open files in a menu in the right side of the tab bar.