is abused for many different features. You can either make UltiSnip use instead of , or you can patch UltiSnip to behave like snipmate, or you can use to insert a tab, or set sw properly and use ctrl-d ctrl-t and > < mappings to change indentation.
The README should also make clear that there are differences to SirVer, focusing on being able to use honza/vim-snippets, focusing on bringing features from snipmate to UltiSnip, such as "completion" menu.
If you really care about this behaviour, tell me again, and if multiple people think this is a show stopper I might work on it - I also gladly accept patches :)
Just remove my snipmate and install this. It works well when I click tab.
But when I press tab, it doesn't insert tab for me.
updated: just try SirVer's version, everything is ok.