I'll start out by saying I REALLY like the Merrell Trail Glove. It is the only shoe I've ever put on where my feet say "I'm home". The toe room is second to none (so far). I liked these shoes so much that after just a couple runs in them I bought a second pair (the ones in the pics below). I've been adapting very well to the zero-drop aspect, and even the lack of cushioning (to me, barefoot purists think they have too much) hasn't been a bother. I prefer to run in them off-road, but that's the nature of the shoe itself -- it is the TRAIL Glove, after all. I've got about 50 miles on the two pair combined now, and I really like them.
That said, if I were in charge of the design, there are still a few things I'd want to change to take this shoe from "great" to "as perfect as it can get", and they're all in the sole and midsole. Hopefully Merrell is listening.
When I first saw the shoe in pictures, I had some concerns about the cutaway underneath the 5th metatarsal (see the white area in the first photo). When you walk barefoot, does this part of your foot not contact the floor? Mine does, for sure, and I'd bet the same is true for most people. The 5th metatarsal is a weight-bearing bone along its entire length, not just at the forward head. Merrell needs to add a little more material here to come to more of a straight line between the base of the little toe and the heel. The shoe upper does a wonderful job of hugging the foot in this area, there just needs to be some added sole to this area as well.
Second, when you place the shoe on a flat surface, you can see an arced gap from the heel to the forefoot (see the second photo). This goes in concert with my point above, in that the shoe essentially has two contact areas -- the heel and the forefoot. They've done a very good job with having a zero-drop shoe, no differential between the heel and forefoot. But this gap... How about keeping the same thickness along the entire outer edge (under the 5th metatarsal)? A bare foot makes this contact, and I believe the shoe should as well.
Lastly, I have long toes. I'm sure I'm not the only one. It's a reason that Adidas shoes do NOT work for me. The ball of my foot falls farther back than average. The Trail Glove sole and midsole start to taper off just behind an average ball-of-foot location. Which means that the ball of my foot is on this taper. If that sole and full-thickness midsole were extended just a quarter inch aft in this area (see white area in the third photo), it would be perfect. Some might say I should have gotten a half size smaller... but if I'd done that, my toes would have made contact with the end of the shoe. Not good.
I realize that Merrell carved every iota of material it deemed unnecessary. The result is a very good, very lightweight shoe. It IS very comfortable. I just think that, with the addition of a little bit of material, it would become, at least for me, as close to a perfect shoe as possible, would add very little weight, and would not become uncomfortable to those that find it comfortable today.
Merrell, are you listening?