I was fortunate enough to win these from a Zen-Ray contest here on the Bird Forum and I will be unsparing in my comparisons with some excellent binoculars that I own.
They are indeed nicely over-built; like a tank in fact and hefty, with really clear optics. A nice padded case included as well. And as others have noted, have a distinct "new binocular smell" (OK: they smell like rubber but that didn't last) that I don't recall on the others. I really like the grippy armoring and their added weight stabilizes these in actual use (like on a rocking ship). Since they are fairly heavy, I got a Leupold harness for these and that made all the difference in the world. While their stock neck-strap is pretty good, it is not enough for the swinging weights that these become when walking with them.
I've taken them on a cruise and and the images through these are super-crisp with a 3D quality that I did not expect from a roof.
I've compared them to a pretty good field: My Nikon 8x32 SE and the Vortex Viper HD 8x32s, and the Altas Optics Intrepid 10x42 EDs.
Compared to their nearest cousins that I have, the Altas Optics Intrepid EDs 10x42 (Silver-coated prisms) (which are practically identical to the Zen-Ray ED2s) the field flattener effect is definitely better, with a larger sweet spot, extending to about 90+% of the field. In fact, you would need to artificially train your eye towards the outer edges to really see where the soft blur begins--from a practical point of view, it is excellent--maybe not as immersive as a Swaro or Zeiss but every bit as bright and crisp.
Here's something I did notice when adjusting them: the right diopter ring does not lock (like the Vipers) but is nicely marked and has enough resistance that it probably not move much in practice. The Vipers and SEs have a great feel in the hand that I missed in the Primes (I often felt like I was carrying a rubber-coated brick with the Primes), but they again are very different in size and weights too.
I also liked one thing in particular: the Primes have a really excellent smooth focus wheel (a fact that maddened me about the Intrepids was that the focus was sloppy and had too much play)
The Intrepids are slightly lighter (1 lb 11 oz) to the Primes (just under 1 lb 14 oz). And the Intrepids are 3/4" longer as well. The eye-cups on the Primes are indeed large, but so far with my glasses, I've not had any issues.
The SEs have a much deeper field of field than any of these (and I'm not sure why--maybe because they are the only Porros?). They are the brightest binoculars I have and a joy to look through. But the Primes held their own in similar good lighting conditions. The only thing that the Primes don't do as well is have as good an ergonomic grip as the SE porros. But in every other way that counts, these are actually on par with the SEs for color balance, brightness, and even give the 3D effect a run.
Probably the only thing the Primes have over the SEs is the great, precise focussing knob; making the SEs feel stiff.
Compared to the very compact and versatile Vipers is not quite a fair comparison with the degree of magnification of the Primes making all the detail 'POP' compared to the Vipers. The Vipers have maybe a touch less crispness than either the SEs or the Primes, but they are highly portable and packable, which is the only downside for the Primes.
On a recent cruise, in the real world, the Primes were excellent in every way that mattered. I never felt like I had to baby them. Their lens caps are all reasonably tight-fitting and never fell off. Their clean finish, styling, and grip was exactly what I needed.
I'm one of the few people that do like thumb indents and they probably could use thicker armoring or softer areas under the armor to cushion the thumbs, but this is honestly a minor quibble.
I can say that these compared as good or better to very tough competition. I even briefly asked two birders, one with a Swaro 10x42 EL, the other with a Zeiss 8x42 FL to rate these and both agreed that these have excellent glass.
I highly recommend these and look forward to Zen-Ray really making themselves a viable comparison with quality European Alphas, because in practical terms, you are not getting much more for thousands of $ more.