Tuning boxes arent all bad.
On my last car i used one, and it was ok. Power and torque were up and it didn't smoke too bad. Over all it was a reasonable mod for the cost, but not quite enough. I sold the box and got a remap instead and it was better. More power, more torque and no smoke. Cost a bit more, but the increase was worth it, so IMO i pay the extra for a map on all cars.
Just don't try fitting it to a car with a map on or you will have big problems.