I've had these a month now and am glad I tracked them down in the size I needed. With that said, size like you would a boot rather than a running shoe. At least that was the case for me (sizing down). I found them comfortable out of the box, although I was in and out of them.
I've worn them with socks and without. While I prefer to wear them barefoot, they do rub against the top of my toes and chafe as of now. I don't mind wearing them socks even if I get wet, though they don't dry as quick as the shoes themselves. Which the drying isn't super quick and dry best in sun. The Altama's hold smell somewhat but bad odors don't linger forever.
The thick rubber soles holds up well outdoors and on rock, trails, sand, road, and water. They look great (I got gray) and can be dressed up or down easily. The toe box is wide And has a solid cap. They are flat without added arch support but aren't flimsy. Ideally, lack of arch support should help strengthen the foot anyways. If you stray to far from the intended use when wearing these, they might not be for you.