I had one a long time ago, all they do is reduce the filtering, so presumably more air will enter the engine, but at the expense of reduced removal of air born stuff that the original filter would remove.
The one i had also created more induction noise, which could be sporty, or annoying, depending on your mood.
Any power increase, if any will be small. I don't see how it will reduce smoke, which is usually a result of over fuelling.
The only real advantage is the ability to clean out the filter, and reuse it. Maybe worth having if you diy, and intend to keep the car for some time?