I dont care about the brand- if its a good one..its good! lol I love this one. http://www.statelinetack.com/item/mustang-microsuede-bareback-pad/WIM01/
I dont have that one- but I was thinking of buying it for my holsteiner HUGE withered mare, but decided I would probably fall off with a trot like hers and 1 misbounce lol.
The good ones generally cost $40-$70.
You can get the super amazing ones anywhere from $100-$300
Pros for you- you get a better seat, stronger legs, stronger core, with PROPER riding, you get softer hands, seperation of seat, arm, leg (instead of your leg arms moving violently with your seat in the sitting trot).
Pros for your horse IF YOU ARE RIDING CORRECTLY- The horse will become softer to your seat, hand, leg.
Cons for you- easier chance to fall off obviously. if you arn't riding correctly, you can develop gorilla arms from trying to balance. Where you stick your elbows out and through your arms forward, curl up your rists etc.
Cons for the horse- since your chances of falling off are higher, if you do fall off the horse will quickly learn how to get you off. If you arn't riding correctly- you can cause the horse to duck behind the bit, be afraid of contact, cause the horse to 'run' in the trot or canter. cause the horse to be off balance, etc....