They are very good bullets. I used one a couple years back to take a decent buck.
The one complaint I hear often is people claiming that they do not expand. I never recovered the bullet I used that day, however I have seen first hand evidence of their expansion. My bother in law took a doe at an undetermined distance (although I was told it was mighty far) with a 250 barnes and 150 gr of Pyro pellets. The recovered bullet was mushroomed beautifully and was pretty close to the picture on the package. Of course 1 bullet is not a good indicator. In the book Modern Muzzleloading for Today's Whitetails by Ian McMuchey, he shows pictures of recovered bullets including a good selection of Barnes bullets. Many of these are expanded although some have very little to show they were even shot!
My personal issue with Barnes Bullets is cost. At a buck a pop they can quickly deplete your hunting budget. The only reason I was able to use them was due to picking them up on the clearance rack for less than half price that spring.