The '//c+ was Apple's last attempt at shipping a new Apple 2-series machine. It was released with a whole lot of optimism... most of which was not warranted.
It uses the same Frogdesign form-factor as it's namesake the Apple //c, with only some minor case modifications, such as a volume slider where the 40/80 column switch used to be (though they kept the Dvorak keyboard switch for some unknown reason), and a standard 3 1/2 inch disk drive versus the older 5 1/4. It also ditched the older external power supply (the brick on a leash).
It holds the title of fastest stock Apple 2 ever produced, with it's little 65c02 huffing along at well over 4mhz, and it's memory expandable to over 2 megabytes.
All that having been said, the //c+ was too little too late. Back in the heady days of 1988, the Apple world was still loving the Apple IIgs, and what consumers really wanted was a slotless GS -- instead, Apple gave them more of the same, old, recycled //e design that had been around for 5 years.
Ed.: The 'correct' spelling should use a double-slash ('Apple //c+') instead of a double-I ('II') -- the node titles uses the 'II' convention so that this node may be more easily accesible by the Average Noder.