I LOVE it. It took a little doing to install; I had to do a Java command from within the Windows command line and install it using a USB cable (the over-the-air download did not work), but the instructions were on the website. It calculates everything you need for technical dive planning using either a Buhlmann or VPM model. It will calculate runtime, OTUs, CNS%, ideal mix for a given depth and desired Equivalent Nitrogen Depth (END), deco schedules, Van der Waals gas mixing, all with whatever Nitrox or trimix you program; you just tell it the O2 and He fractions in your mixes. It also calculates gas usage for a given dive plan based on your working and deco SAC rates, and it computes multi-dive profiles. In short, it does everything you need desktop deco software to do.
Now, it doesn't do pretty graphs or take advantage of Blackberry's superior user interface, because it is designed to work on any Java-enabled phone, but still, with it I don't need my laptop on the boat anymore....