I brought a Carly about 4 months ago as I needed to register a new battery to my 5 Series and not having a windows laptop I wouldn't be able to get ISTA to work.
About 10 years ago I bought a cheapish OBDII reader and it was fairly rubbish, so didn't really want to go down that route.
After a while Googling I decided that a Carly would be best value, as they only wanted £75 for the year including the Bluetooth dongle and seeing as I would use it on other cars.
So far its done everything I've needed it to do and the coding has been a bonus (roof up and down with the key, double flashing hazard, all brake lights on at the same time and stuff on the 5 series too). I've also just bought a Fiesta for the daughter and used it go check a few cars and ruled out a couple because of historical problems I found.
So when the year is up I'll be looking for an OBD reader thats good for Beemers, but also other cars.