I love Google Tag Manager, but it has a steep learning curve - and the UI doesn't always help in that regard. Take, for example, the 'tag firing options' which determine how tags fire on web pages. Pretty fundamental, right? And there are only three options to choose from - Unlimited, Once per event, and Once per page:
I'd really love some tooltips right there in GTM instead. Some of the other options have them (ie they are part of the UI), and the information already exists in Tag Manager Help, so it should be pretty trivial to add them in. Why not a tooltip on every option? You never know what a user is going to find confusing or forget.