We have toyed with the idea of buying one of these for a few years, so she solicited suggestions from those who already own such devices and ended up ordering this one.
We picked up a couple of steaks yesterday and tested it out for dinner. It worked well, but I definitely took away a few lessons for the next time we use it (possibly this coming long weekend).
In terms of lessons, the first change I will make is to get steaks that are smaller, but thicker. I might lower the cooking temperature a couple of degrees as well, but I think 58C would have worked fine if they had been a thicker cut. I seared them in a cast iron pan after they came out of the water bath, and it pushed them past medium-rare into medium/medium-well territory.
We've already decided that we are going to try chicken next. I've head wonderful things about chicken breasts cooked by this method.