Shoes really matter, but not for the reasons most weekend warriors think.  For example, if you spend a lot of time looking for high cushioning and support, or if you buy shoes because a sales guy at the running store put you on a treadmill and video your feet to show you how a certain shoe "corrects" your stride, you might be caught off-guard by the Inov-8 approach.

Here's why:

During recent decades, running shoes have been designed to help initially prevent injuries in poorly conditioned legs and feet by building shoes that replace natural body functions with artificial stabilization and extra cushioning.  The resulting problem is that the person using those shoes initially becomes more aerobically fit and starts running faster and longer... without their feet and legs being structurally strengthened to handle the increased demand.  Before long, the shoes can't continue to compensate for the fact that the person's feet and legs' inner structures simply aren't trained to handle the running.  It's too-much too-soon meets too-little too-late.  Consequently, painful "overuse" injuries (shinsplints, knee pain, back pain, stress fractures, tendonitis, fasciitis, etc.) are practically an inevitability for many well-intentioned and dedicated aspiring runners who take up jogging or join a cross country or track team.

A very large number of "overuse" injuries in otherwise healthy people result from a combination of two factors.  1) Weak/underused feet and leg structures, as described above; & 2) Bad running form - it doesn't immediately hurt to run improperly on 2" of cushioning, but bad form will catch up to you as you increase mileage.  Really, the problem isn't "overuse" so much as "use" when, thanks to laziness and bad shoes, critical parts of our bodies are only conditioned to "under-use".

The solution is to make the following transition: Stop running in shoes that put us on a cushy path to a painful destination and carefully learn to run in shoes that enable our bodies to run the way we were actually built to run.  Most people are completely capable of much more running than you might think, but it takes a little work to correct years of under-use. This transition will require a little patience as you build the strength in your legs and feet to avoid injuries.  It will also require learning to run with healthier running form, which is a lot easier on your body as well as more efficient for long distance.

Inov-8 shoes are designed to enable your foot, not to support it to the extent of replacing natural foot functions.  In other words, if you are out of shape and decide to start running 20+ miles per week exclusively in this shoe, you are taking a risk.  The shoes are designed for the runner who is making or has already made the transition as described above.  Inov-8's entire product line is built on a minimalist philosophy. More and more runners and fitness buffs are realizing that the Inov-8 approach is, indeed, a better approach.  (Not to mention a darned good shoe in terms of materials and quality as well as design.)

If you have not carefully transitioned to a minimalist running style and built up strong feet and legs for this type of shoe, a sudden switch could injure you.  Take the transition slowly because your feet and legs need to get strong enough to actually do what they are built to do.

Inov-8 shoes are generally comfortable, very well built, and perfectly able to carry a fit runner through many hundreds, and even a thousand, happy miles.  However, they do not replace under-used arches or compensate for pounding, heel-striking strides. (Contrary to popular myth, flat-footed runners can run just fine in these shoes - if they get their feet and legs in shape.  Flat feet are not the running liability many have been lead to believe.  See the "comments" for more on flat feet.)

How can I say all this?  I have flat feet, terrible pronation, and am 6'3" tall.  I ran four years of cross country in high school and was on the varsity squad for a state-championship team.  The whole time, I fought miserable shinsplints, knee pain, and back pain.  I popped Advil like tic-tacs.  I loved the sport and ran relatively good 5K times but my chronic pain was bad enough to sideline me for all of track season senior year.  Any time I increased my intensity or mileage, the problems got worse.  Doctors were talking about "scar tissue" and "surgery".  Well-meaning doctors told me to stop running.  They said my body just wasn't made for it.  Shoe-store employees continued to put me into higher support, more motion control, more cushioning to try and "correct" my feet and legs.

It wasn't until college that a former teammate (who is now a professional runner partially sponsored by Inov-8) explained the concept of minimalist running to me.  Although I was in good aerobic condition, I spent a month resting and then the better part of three months carefully re-training from scratch, patiently overhauling my form to be more efficient, working my way into exclusively running in racing flats (Inov-8 wasn't available yet), and allowing my feet and legs to get much stronger and more flexible.

Since then, I run further and faster than ever before, with no more "overuse injury" bullcrap.  My training mileage has at one point been greater than 90 miles per week.  I have competed in a major marathon and placed in the top 4 in my age group.  I have won a handful of smaller races.  Better yet, I have not been injured or hurt ONCE since I made that transition to minimalist shoes and better running form.  I haven't even owned a pair of traditional "trainer" shoes in over 8 years.  (Much of my training is in an old pair of trashed racing flats with at least 1,500 miles on them.  I prefer to use Inov-8 for more rugged terrain and tougher trails, where they excel, but they have models that make good trainers on almost any terrain.  When my beloved racing flats finally die, I'll replace them with an Inov-8 racing model.)

I consider myself a "weekend warrior" and I am a far cry from an "elite" runner.  Had I listened to the well-meaning doctors who told me I just wasn't built to run and should give it up, I would have stopped years ago.  Inov-8 understands that we humans are literally built to be running machines.  Tap into it, and enjoy.