RTTI subscription (in the USA) is for 36-months, and if you want to continue it, costs $200/year (along with a few other connected drive functions). Depending on where you live and when and where you drive, it can be useful. Mine expires later this month (in about a week), and given my use, I'm not planning to renew it.
The i3 does not have OTA map updates (yet), so if you want to do them, you either pay the dealer big bucks, or go to someone else and do it yourself for LOTS less...you do need to get a VIN unique code to make it work. The biggest hassle is downloading all of the map data, but the actual install is pretty easy - insert a USB stick, enter a code, wait for it to install...pretty simple.