I've owned the BT since late 2016. I bought the car as I wanted a vehicle that I could utilize for daily driving, picking up the kids from school, towing, camping and for going out bush for four-wheel driving. I was originally in the market for a Ford Ranger XLT, however I opted for the not-so-good-looking sister - the BT-50 - on the basis that it was $8000 cheaper and also down to the fact I have a good relationship with my local Mazda dealership. My personal experience with after sales service with Mazda is that in the event of an issue they will honour their end of the warranty with out a fight. In comparison to the Ranger, the BT is the no-frills version, which depending on who you are, may or may not suit you.
While the BT is by no means a race car, it is quite quick for a vehicle of its size and can hold its own off-road. I've taken the BT a number of times to the powerlines east of Perth, even when I only had the highway terrain tyres on, and it went everywhere the beaten up 4x4s went, albeit without the luxury of air con. The 3.2-litre, while thirsty compared to the smaller dual-cabs, hauls ass when you put the foot down.
My dislikes with the BT is the infotainment system - which seems to malfunction right when you want to use it - and a clunky gear box (a 6-speed auto). Also, the rearview camera takes some getting used to as the vision is displayed on the actual rearview mirror. The wheel offset is a not-so-common offset, so trying to get aftermarket wheels that don't poke out of the guards or exceed the legality of track width for your state can be difficult.
Reliability-wise I've had no issues, aside from the Infotainment system, which seems to be addressed in the later models with an Alpine unit. Overall, I’ve experienced no breakdowns.
As an improvement I would like to see the BT-50’s dash cluster upgraded to something similar to that on the Ranger. However that is something that would be reflected in purchase costs, which is one of the reasons I purchased the BT-50 over the Ranger.