I know some folk say that you should ignore the numbers and just ride a bike to see what it's like. But there are a few problems with that approach. First, life is too short to test all possible bikes and second some of us just aren't that good at telling how a bike will perform from a (short) test ride and often just end up testing the tyres and contact points rather than the bike.
I reckon that, in theory at least, it should be possible to predict how a bike will perform from the numbers. Given that most bikes are pretty good these days then the numbers should tell you whether it is the right type of bike for your needs. But which are the numbers that matter most on a mountain bike? For example, does anybody think they could tell whether a bike was likely to suit them based just on travel, wheel size, head angle, BB height and chainstay length? I'm assuming that you can pick a size to fit and tweak things like bar, stem, saddle to suit.