We have one in our ACE and have found it to be quite useful. The grandchildren use it not only for sleeping at night, but as their "secret fort" where they read, play games, play with dolls, and do other such kiddie things. We've also found it to be a useful storage area when I need to store a number of large suitcases, rifle cases, or other similar items (such as when we go on hunting trips).
The only downside I've found is that I'm always forgetting it's down and clonking my head when I get out of the driver's seat. It's not a problem with the bunk, it's just a factor to consider if, like me, you have no brain. :)
Skip