I’ve been using sublime text 2 for a while now. I know the beta of version 3 has been ongoing for a while but the last time I tried, I had some problems with the addons/packages.
I ran into a few problems when upgrading. The main one seemed to be caused by some old configuration files for packages.
I tried the suggested upgrade of install subl3, install the new Package Control system, copy your old packages but do not copy Default or Package Control. This worked but I still had some weird issues with the sidebar and the tabs.
In the end I deleted the User folder from Packages and started again with my user prefs.
One other tip once you have removed sublime text 2 is to symlink subl to subl3.
I keep a list of sublime text addons/packages I have installed on github