MTB reviews are one piece of the puzzle. What I like about that site is after you've filtered out all the non-specific praise ("this thing rocks!!!!") and the knucklehead complaints ("duude, I bought this 18 pound cross country racer and the front triangle broke after just one 8-foot drop!!!) you can get a broad sense of what people are thinking about a product, and it's helpful when you see a bunch of people who've had the same specific problem, pointing to some design or production fault to avoid.
Magazine reviews are tricky, for the advertiser reasons noted above, but I think they are still valuable as tools if you don't rely on them exclusively. Mountain Bike Action, for example, are certainly opinionated about the brands they like and don't like, and I know that colors some of the reviews, but they've never seemed shy about pointing out a products' faults, and there are some things they really pan, so I don't think they're complete slaves to their advertisers.
I think the best strategy is to read the reviews online, read the reviews in the mags, talk to friends/people on the trail that have a product you want, and most importantly, ride the bike and make your own opinion. It's more likely to be the right opinion if you've found out everything you can about a product.
As to Jamis, I've got a couple of friends who ride Dakars, and they speak very highly of them, FWTW. One more tidbit; apparently '03 was the last year Jamis used a true Horst link rear. Supposedly they tired of paying Specialized their royalty and moved the pivot up onto the seatstay in '04, and it doesn't pedal quite as well as the older ones. But hey, don't listen to me - get out and ride one!