Four months ago I got a Zacuto Z-Finder Pro for video and instantly fell in love with it. I immediately started using it for stills with great results and over the last few months have gotten very comfortable and fast composing the shot, punching in to 10x, focusing precisely, the firing off a shot. With the Zacuto it looks like you are composing on a huge 10 foot screen in front of you. At night, the screen is incredibly bright and you can see exactly what your exposure will be before firing off the shot.
Is it as fast as shooting through the viewfinder and using auto focus? Certainly not, but to have a 100% hit rate on the focus when shooting at 1.2 more than makes up for the lack of speed.
What's really cool, is I can see the chromatic aberrations disappear when the focus is absolutely locked on to my subject. Just a mm makes a lot of difference in the amount of CA and I don't think autofocus is that precise even when it works perfect.
I have also used it in the studio with strobes with excellent results as well.
I think it's a great tool for anyone struggling with the auto focus at thin DOF or anyone who wants a really bright viewfinder for nighttime street photography.