I've had a paid of 12 x 50 Ultravids for about 10 months now. They seem very bright for a glass of this high a power and they're very sharp across most of the field with a little softening towards the edge. They have an extremely wide 69 degree apparent field and a 5.73 degree true field and can focus as close as 11 feet. Their eye relief is 13.8mm which would be a little short for people who must wear glasses. However, I don't have to so that isn't a problem for me.
I used to have a pair of the 12 x 50 Nikon SEs. Those are also excellent but I like the Leica's better for several reasons. First, their true and apparent fields are almost 15% wider and their total field area is 30% larger. The Ultravids give you more of a picture-window wide field of view. Second, they're rugged, waterproof, and their compact size makes them easier to pack in a backpack than the porro prism Nikons are. Third, even thought they weigh 5 ounces more than the Nikons, I find that I can hold the Ultravids steadier for longer periods of time than I could with the Nikons. Even though the Nikons have great ergonomics for a porro, I find the ergonomics of the Ultravids to be even better.
While I think that the 12 x 50 Ultravids are easier to hand hold than the Nikon 12 x 50 SEs, that doesn't mean that they're easy to hand hold. When I use them I always try to find somthing to sit on, or a tree/post to lean against, or a car roof that I can brace my elbows against. When I have support like that I find that I can hold them reasonably steady for long enough periods of time to make the viewing experience worthwhile. However, even with aids like those the shakiness will become noticable much more quickly than it will with a pair of say 7 x 42s or 8 x 32s.
I would not recommend a 12 x 50 as one's primary binocular. The pair I have nicely compliments my 8.5 x 42 ELs. And if prefer having those two binoculars (each of which excel in their own way) to having a single 10 x 42 or a 10 x 50. However, if I could only have one binocular my first choice would be the 8.5 x 42 ELs and my second choice would be a high-end 10 x 42 roof prism binocular.
One earlier poster mentioned using the 12 x 50s with a monopod. I will have to look into that. If I could find one that worked well, was not too heavy, and that packed easily, it would be nice to take one along on some of my nature hikes. I have used the 12 x 50 Ultravids with a larger binocular mount and they really do perform very well on one, but the downside is that they're not as portable or easy-to-use when mounted as they are when hand held.
. A few versions of Finnsticks can be spotted in 
