I have the Neptune washer/dryer (stacked) set, courtesy of the Boston Washer Study sponsored by Maytag a couple years ago.
The dryer is great, very large and does use less energy than my previous Maytag model. It has several settings to select from, depending on your load type. One thing I've found is that for smaller loads I prefer to use a timed setting to make sure items dry properly. I've had no mechanical problems with the dryer.
The washer uses much less detergent, water and energy than my previous Maytag model. It does make a wild, spinning sound at the end of the cycle which you have to get used to (if you get the washer). Laundry comes out nearly dry after using the optional Max Extract setting. I have had two computer problems since have the unit installed.
Repair of these models is VERY expensive so consider that when you purchase. I ended up buying an extended contract when I had the second service done on the washer.