The Bruizer Pro is a well-made blowback gun. Nothing really fancy about it, but it does the job and it does it well. The gun is well-made and feels good in the hands. The gun also proves to be reliable as it has not let me down yet. Simple to take care of, but a solid performer. Good accuracy w/ a good upgrade barrel -- I've use a J&J Ceramic and a Lapco Bigshot with good results.
The expansion chamber, like most x-chambers, is of dubious value when it comes to really maintaining shot-to-shot velocity consistency. But, in conjunction with an anti-siphon tube in your CO2 tank, you shouldn't have a problem with liquid CO2 being sucked up into the gun. The x-chamber makes a very good vertical foregrip, though.
The only significant downside to the Pro is the fact that it uses VM-threaded barrels -- and they're not easy to come by. However, there are still some very good barrels available in VM-treading, such as the Lapco Bigshot.
These days, the Pro really isn't a serious contender as a new gun. You can probably get the same quality from a Piranha or F4, and not have to worry about finding VM-threaded barrels. But having said that, Nu-Line really does make good products (I bought my step-bro an Outlaw) and their newer guns all take Sypder-threaded barrels. In other words, if you want a new Bruizer, get a newer model than the Pro. But if you're looking to get a good used Bruizer, there's nothing wrong with the Pro.