The most unique thing I love is that "part-time" agents are free. Part-time being any agent that responds to fewer than 10 tickets a month. That means my devs can all have accounts to get in and look at the occasional ticket, maybe even respond, without paying for accounts for everyone.
It also "just works" which is great. It was easy to setup triggers and canned responses (which include rich HTML like links and tags for things like customer/client names, dates, etc...)
Support has been readily available via live chat, email and by phone, and Teamwork support has really been wonderful both before and after signing up.
I also loved their free trial that lets you actually switch plan levels while in trial so you can actually see what features are included vs. not. That let use deterime the mid-range plan solved all out needs and saves us a lot of money.
Review collected by and hosted on G2.com.