Pros:
The bumpers are quite steezy. They hold up much better than stock, fully protect the battery box, and provide additional rail protection. They are also noticeably slicker than stock and have felt good for curb nudges and tail drags. Also, they're currently half the price of BANGs.
Cons:
The brackets, while an excellent idea, appeared to lack precision machining. Mine were bent slightly, causing both bumpers not to sit flush with the bottom of the board. I was able to correct this somewhat by bending them, but it still left gaps on the sides of the front bumper, which I sealed with super glue to keep excess dirt and water out. Secondly, one of the brackets had slightly misshapen screw threads in one hole, causing the black coating of the screws to strip off (tested with multiple screws), clog up the threading, and get the screws stuck half way in. I remedied this by applying lubricant to both the screw and bracket, driving the screw in to the point of clogging, retracting it out, then cleaning both the screw and bracket threads, and repeating many MANY times until all the screw's coating was removed and the screw would go all the way in without jamming.
All in all, very happy with my setup now, but it required a lot of extra work to overcome the defects. If it weren't for the reduced price and the fact that white BANGs were out of stock at the time, I'd say there is no reason to ge these over BANGs.