My wife uses one. It's not a bad computer, but it can be a pain in the ass sometimes to get paired, it's more expensive than you need, there is no way to switch off the transmitter, and the battery in the computer itself only lasts about 4-6 dives before it needs to be recharged.
That said, unless you really want the air integration and are looking at spending that kind of money....I would buy a Shearwater Petrel...I have two, will be buying another to replace the wife's Icon HD, and I love them.
It IS a great air integration computer when it works right and they did just come out with a new set of firmware. It can compute SAC on the fly, Time till empty and so on in a very nice easy to read, graphical representation of the tank you are breathing and can do so for up to three tanks with different gases at a time (have to switch between each gas of course).
I can give you a complete list of likes and dislikes if you wish, but in short, had one in the family for many years, buy something else.
Finally, if you REALLY want an ICON HD and transmitter....sell you one for cheap. (no joke. getting rid of ours)