This is quite a big subject, but in essence, there's no real evidence that gait analysed training shoes help prevent injury. They did a large study in the US using soldiers, a bunch of whom were gait analysed and given appropriate footwear, and bunch who weren't; they were just issued with a neutral training shoe.
Guess what? There was no difference in injury rates between the two groups.
From my own experience, I joined the army when they were still issuing plimsoles and boots; that's all we ran in; and we were fine. I seem to remember one lad did claim to be suffering with shin splints, but the troop Corporal cured that with a good shouting session.
I'm far from any expert mind, but I believe running form is more important than the training shoe. Take a look at Chi Running, natural running, barefoot running, Alexander Technique; I think they're all similar and teach a forefoot/midfoot landing, shorter stride, faster cadence, upright posture, etc.
A good best selling book is Born to Run also, and it covers some of the issues surrounding modern over-engineered training shoes, also Panaramas The Truth about Sports Products covers this too:
http://www.youtube.com/watch?v=4Rul7XbM844
Many runners say it's important to find out what works for us as individuals though, and I don't disagree with that either; just giving an alternate view from the mainstream.