I've never had one in a WSM caliber. I did read they had some magazine issues that caused jamming, but I've never owned one so can't confirm or deny that. I also think it's a much better option than any of the Remington semi auto's, but that being said
I had one in a 30-06 and it was a decent deer gun, but it wasn't something that was a good range gun as it just wasn't nearly as accurate as I'd have liked.
I had a heck of a time trying to get it sighted in and every time I shot it at the range I got frustrated. Then I would think about how much I spent on it, and get even more frustrated.
When I first got it, I couldn't get it to shoot anything decently. I tried to sight it in with Winchester Silver Tips and it was hitting all over a 8" target. I then tried Winchester Power Points and while the groups shrunk, they were still huge. Finally I went and bought a ton of different factory ammo to try. The only two that shot halfway decent in it were Federal Power Shoks in 150 grain and I got groups that averaged 3" at 100 yards with them, and the Federal Fusions in 150 grain which shot the best out of everything I've tried and I got 2" groups pretty consistently. This gun will not shoot anything else that I've found in it.
To me 2" is still pretty disappointing, but it was at least usable with that. 8" groups with the other ammo wasn't useable. I called Browning and explained the issue to them, and they told me that I was welcome to send it in, but that there really wasn't anything they could do for me as any groups 3" and under were within spec.
So I learned to live with it, and for deer 2" and 3" groups were fine. That's why I say it's a great hunting rifle, but the accuracy just sucked.
I started doing research online and talking to many local gunsmiths, and other guys that owned them locally trying to figure out how to improve the accuracy, and nothing I did helped any. I've seen a couple posts from guys online claiming theirs shoot sub moa groups, and a few more claiming theirs shoot 1" groups. However, I've seen a bunch more complaining of the accuracy I'm getting, and that they could only get that with one or two types of accuracy. A call around to the local shops revealed many of them had seen the same things with the guns. One shop owner told me he personally had one and found a handload it shot decently, but he'd never been able to find a factory load it would shoot well. The reports of poor accuracy just by far outweighed the good reports. This makes me think that while I'm sure there are ones that shoot MOA out there, they seem to be the exception not the rule.
After I started handloading I tried to work up a load for it, but I never was able to get handloads to shoot decently out of it. The best I got was about a 4" group, so I just always stuck with the Federal Fusions.
Now, the accuracy aside, I like the rest of the gun. They have a good feel to them, they are beautiful guns, and they are extremely reliable for a semi auto. If you can deal with the sub par accuracy, they are great hunting rifles. Several friends have Remington semi auto's and it's no comparison between them and the BAR. They also seem to be inaccurate, only they are also unreliable. So between those two the BAR would be my clear choice.
There is also the Benelli R1, that's gotten great reviews, but I've never shot one so I can't comment on them.
Overall, this is my experience with one and if I had to have a semi auto hunting rifle I'd take a look at the BARs. However, if I wanted accuracy, I certainly wouldn't buy one.