Everything you need and nothing you don't. Transmission includes critical features such as a block list function, global bandwidth limits, speed limits, NAT & manual port assignment, Remote desktop management, Seeding and Queue limits (I suggest stop seeding at ratio: 2.00 or a greater rati...
For such a tiny app, with a very limited function, idle most of the time, it actually is using non negligible processor ressources (frequently around 2% when not in use, and totalling more than Alfred, Dropbox or 1Password, for example).
Have an application from Windows you just can't find a better alternative for on the mac? Use Virtualbox and try on the seamless mode and you can use your trusty windows software on your mac providing it's not insanely processor or graphic card heavy.
Applications with daemons or launch agents may not uninstall properly. It is recommended to search for uninstall instructions even though you may be using this app. Even so, it tends to get .plist files and the likes.