I'm about 3 years into my transition into minimal footwear. It started with a pair of Inov8 295's 3 years ago and initially could really feel my foot muscles being worked, but grew to really enjoy the much lighter weight, more flexible shoe.
Fast forward to one and a half years ago, I bought a pair of VFF KSO's and these are what got me back into running after years of knee pain. It was a slow transition, but basically they retrained me how to run with proper form. I even wore them down to -5F snowy runs with 2 pairs of Injinji socks, yeah I was definitely pushing the limits of their use. I wore them for trail running and for hiking, but found that I was constantly getting grass and twigs snagged between the toes which I found really annoying. I pretty much only use these in the gym now and for easy runs on paved/gravel urban trails.
Over the last year I have tried out the Feelmax Osmas and the Kuuva boots and really like them, but the traction is horrible on them if you will be dealing with any wet, muddy or snowy conditions. I have since sold the Kuuva boots for the very reasons Damien states above. I have worn the Osmas some for hiking, but since they are so minimal, I found myself having to pay so much more attention to the trail looking at what I was stepping on instead of my surroundings. I think over time my mind will catch up and I will be able to scan the trail in front of me and my feet will automatically find their footing. Also, I have found over time that my body automatically adjust the weight-bearing depending on what I am stepping on... Not sure how to really explain this more. As for the look, I personally kind of like the retro/European look.
I bought a pair of New Balance MT101's late last fall and have really like them for trail running and hiking, although, being in MN, it has all been in snow so far. I even used them for snowshoe running. They don't fit Damien's definition of minimalist (which I agree with), but they are about as minimalist as you can get for a traditional trail running shoe. I am finding that the more I wear "real" minimalist shoes, the less my feet/body like a traditional shoe. And this goes for even off the trail.... anyway, I bought a size up from my "normal" size and took the insole out and have found these to be doable. I have thought about cutting the heal off of the sole to make these closer to a zero drop shoe, but just haven't quite gone there yet.
I won a pair of Terraplana Evo II shoes, but didn't really care for them that much as I didn't like how the uppers don't stretch. They are a pretty stiff shoe for being minimalist. I will be selling these.
I have been wearing the Merrell Trail Gloves now for about 1.5 months (gravel trail running and snowpack trail running) and really like them. I wasn't real keen on them at first because they feel really constrictive around the arch/midfoot, but they have either stretched out a bit or I have just gotten used to it. These are probably the most ideal shoe I have and certainly will be wearing them a ton for trail running and hiking. The traction is really good (with the exception of mud and snow packed trails). The fit for my feet is excellent!
The last pair of shoes I have tried is the Inov-8 Baregrip 200s. I just got these last week and only have a 4 mile trail run in them so far. They are narrow across the forefoot for me, but the upper is mesh and fairly stretchy, so I think the more miles I put on these, the better they will feel. I will only use these for trail running or hiking in muddy and/or snowpack conditions, so I can live with the bit of constriction in the forefoot. These are a very interesting shoe as the tread is very, very aggressive, but there is no midsole and no heel rise. The only padding you have between your foot and the knobby treads on the bottom is the insole (of which I will probably remove for my next trail run). The trails here in MN are still mostly snow-packed, so I can only speak for these conditions. Where there wasn't snow, the ground was frozen, and this was strange to run on as the large knobby's on the shoes pressed up through the insole into the bottom of your foot. I couldn't decide if it was uncomfortable or if it felt like a good massage. ;-)
On my want list is the New Balance Minimus Trail shoes that just came out. I have tried them on and they feel amazing on my feet. I think for me they are the perfect balance of minimalism and protection both in overall construction and midsole thickness. I think long days of hiking or trail running will require a little more padding under the foot than what the Merrell Trail Gloves have, so this should fit that need. Somehow I need to come up with a little more cash to get these so that I can try them out.
All in all from a physiological standpoint, I feel like I have much better balance and agility wearing minimalist shoes. My previous knee and ankle problems have gone away (although now I am fighting IT Band issues from over-training). There is something to be said about being able to feel the trail beneath you.
I also just want to reiterate the point about transitioning slowly to minimalist shoes. The typical person's feet have basically been in casts for most of their life and the muscles, tendons, ligaments and bone structure are very weak. The achilles and calf muscles will also need time to adjust. Go barefoot when you can as the tenderness of your soles will slow you down or force you to stop before damage is done to the supporting structures of your feet and legs.
As for Chris's question in regards to off-the-trail. I now hate my traditional dress shoes and now own a couple dressier shoes from Terra Plana Barefoot that are my office and casual shoes. They are expensive, but the quality is very, very good and my feet are so much happier.
Sorry for the long post, but I hope some of what I've learned and experienced in the last couple years will help others.