I've been wearing Teva's since the early 90s when they were the standard issue of every whitewater rafter and kayaker.  I have since discovered myriad other excellent applications for this simple, durable and versatile footwear and I wear them year-round (even in snow).  I have a nice "Teva tan" to prove it!

The Teva sandal is fundamentally an ageless footwear design, possibly one of the earliest known to humankind, which has just been re-worked with modern high-tech materials and ergonomic engineering.  I am practically a "barefooter" in my daily life, meaning I don't prefer to have my feet confined in shoes, where they invariably get warm, sweaty, incubate fungus and bacteria and produce odours.  And yet, being barefoot all of the time is not safe, practical, sanitary, or lawful in some places.  So Teva sandals are the next best alternative!  They allow air circulation and freedom from confinement, and protect the soles of your feet from direct contact with sharp objects, filth, contamination, and endless unknowns.

What's high tech about it?  High strength NYLON WEBBING (which could bear your body weight before breaking), VELCRO FASTENERS (and in some models, Fastex buckles), the comfortable SHAPED FOOTBED with arch support made of special ANTI-MICROBIAL RUBBER, and the nice SPLIT SOLE design with TREAD pattern.  Bargain variants of river sandals (Teva clones) may use cheap webbing that will fray or break under load, bad fasteners that make it inconvenient to just slip on and off quickly, a bad footbed can make your feet ache, and without the micro-ban zinc the porous rubber will swell with colonies of bacteria from your feet making the sandals stink egregiously.  Even having decent tread makes a difference on slippery surfaces, and the split sole allows not only a more natural foot flex but also allows for things like biking/riding, and foot accessories should you wish to attach them (impromptu crampons or snow shoes).

The biggest value added innovation to the Teva line in recent years is the anti-microbial footbed.  Teva sandals dry very quickly and they naturally float.

Besides the original intended use as a fully amphibious sandal (which means you can immerse them, swim in them, or be around wet surfaces without damage), they are very comfortable to wear around camp, or around areas of uncertain hygiene when walking around in the middle of the night (i.e. outhouse).  For me, these are essentially my back-up footwear and slippers when I travel.  They conveniently pack flat and fairly clean (placing them sole to sole with their own Velcro straps) in a small stuff sack.  Excellent for the beach, casual shopping, public showers, wandering around inside a hotel or hostel, and even light hiking/touring.

Some UNintended uses for Teva's.  Like, thermal/fleece socks with sandals turns Tevas into warm boots.  One can make instant improvised "shoes" or mocassins with Tevas by wrapping your feet in cloth, fur, plastic, insulation and then strapping on the Teva's for the sole.  As alluded to before, one can use the basic sandal layout as a base for both improvised crampons and snowshoes, or as a template for... improvised Tevas! (using rubber from tires and some cord).  You can also wear it as a hazmat overshoe when you need extra sole protection/when entering very bad, hot or corrosive environments.  I have used a single Teva as a protective pad on my foot when it was splinted and bandaged.  You can throw your Teva's into a fire for emergency signaling as the rubber will burn briefly (2-3 minutes) with thick black smoke.  Similarly, you can improvise small vertical signaling flags THROUGH the soles of the Tevas that will float on the surface constantly without extra work if you find yourself stranded on open water.  I find Tevas a decent choice for either herding or applying traumatic compression to arthropods that wander into my living area.

Finally, I shall mention the common failure points of Tevas, since I have owned about 6 pair (and about 10 of other brands) through my 20+ years of use and field testing.  Most common failure will be, the Velcro (hairy side).  They will start to get less efficient and eventually become virtually useless after about a year.  Luckily, they are easy to replace (sew on or glue on).  The second most common failure point for me is the center front of the sole and the tread on the sole in general.  I know that I probably wear my Tevas more than most people, but I literally wear the tread down to smooth flatness in a couple of years and the center front area usually first develops an erosion hole.  I don't consider this a failure of the product as I put many miles of rough use on them and I don't expect them to last forever.  If you get this model, or any recent model Teva, it should not be a problem, but please recall that bacterial foot stink problem on the older or knock-off versions of Tevas that I mentioned.  Though they are reasonably comfortable sandals after an initial break-in period, I would NOT recommend them for any distance hiking or hiking on loose dirt or sand.  This is because dirt, sand or grit will eventually get under the straps where it contacts the skin and will cause blisters and abrasion injuries.  I learned this the hard way taking a 10km walk along a seashore turning my feet into bleeding hamburger.

Good luck and may your Tevas take you to many new wonders!