I love the Prio. It's my go-to shoe.
I'm 9 months into my pair. This is primary running AND gym shoe. I sometimes wear this as a general walking shoe too, usually when I am on vacation, because it tends to keep my feet very happy when I'm walking and standing for an entire day, compared to any other shoe I have worn in that scenario (about equal to my experience with Toms in that context). I am almost always very comfortable in the Prio. The exception would be when I choose to forgo socks and my feet get wet with miles of running to go; that's when I get a few blisties. Oh, and stepping on certain rocks is not fun in these.
I personally wouldn't consider the Prio an "all-terrain" solution. I prefer trail running, although I run a lot of paved path/road too, and some treadmill (sacrilege!) for hills, since I don't have easy access to as much of those outdoors as I'd like. I feel like the Prio is absolutely great, until you get to anything more technical/rough than a moderate unpaved trail. I don't want to be stepping on many stones (of say 1-2" diameter) in my Prios, or certain roots, ouch. I'm also flat footed, though. I hesitate to complain about their performance on wet and muddy surfaces, because there is no magic solution to that. In my experience, you can have shoes that are aggressively lugged and still struggle in such conditions. I think at that point it's more about your stride, cadence, balance, and the choice of where you place your foot. Anyway, my inclination is to suggest more of a trail-specific shoes for trails. On the traditional/maximal end, I own a pair of Brooks Caldera 2. On the other end, I own the Merrel Trail Glove 4. Why the range? I did all my running in traditional running shoes until the Prio. Now I prefer more minimalist shoes, but as my mileage creeps up, I am contemplating mixing in the traditional ones again (I'm thinking about ankle support and sole sensitivity over long distances). We'll see how well that works, now that my stride has adjusted to minimalism (used to be a heel striker, now it's midfoot).
Other comments:
The wear on the sole of my Prios is less than I would expect, given that this is my primary shoe. Every other footwear I've owned (apart from snow boots) has shown more wear in less time.
My current rotation (for running AND general fitness), in order of most to least frequent use:
1) Xero Prio
2) Merrel Trail Glove
3) Reebok Crossfit Nano 8.0 (gym only, very limited running)
4) Any Brooks shoes I own (Caldera 2, Ghost 8, Adrenaline GTS 16)...very, very rarely these days.
How in the h$ll does the Nano figure in? Before I transitioned to the Prio, I was looking for something more stable to use in the gym. It's kind of blah for running but it's been a good gym shoe.
I recommend toe socks (I like Injinji) for use with the Prio, and with other shoes for that matter. I can comfortably run sans socks in the Prio, but it's more enjoyable with socks on my longer runs and/or trails/wet conditions. I prefer the lighter weight running socks.
I wash my Prios every so often in the washing machine (quick, gentle cycle, extra spin; detergent specially formulated for athletic gear). I let them air dry. No problem. However, I once dried them in the dryer, inside of a small backpack, on high heat. It wasn't entirely intentional, but it was a mistake. That seemed to cause the sole to start separating from the upper around the toes. Maybe the glue was already starting to weaken there before my boneheaded move, who knows. Anyway, the shoes were still comfortably useable despite the partial separation, although arguably more dangerous (I feared the front of the sole would catch). Still, I decided to reattach with Boot-Fix Glue, and this has worked surprisingly well.
If you are coming from wearing traditional running shoes, wearing something like the Prio (meaning flat, low, "minimal") will tend to encourage a more "natural" footstrike (shifting toward mid- or forefoot strike). For me, this was initially a rather weird experience. It is jarring/uncomfortable to continue heel striking in minimalist shoes. So the natural adaptation seems to be to run in a way more similar to what you would do if you were running truly barefoot. This felt different, and kind of wrong, until I got used to it. I also realized that my feet felt better after each run/workout. I would say it took me six weeks to get used to my new running form.
I hope this is helpful to someone out there!