I had a puck type GPS but decided that it was too finicky. When the computer wasn't interfacing with it, it couldn't be used because the GPS didn't have its own display or power source. Often the interface between the two became unstable and the computer couldn't find the puck. With my handheld GPS and a USB cable everything seems to work fine. When the GPS quits talking to the computer (for whatever reason), the GPS is still useful.
I have a plotter and two handhelds already. I want the laptop/puck combo to practise with using SeaClear and other programs with NOAA raster maps.
Basically, it's fifty bucks to evaluate and give me something to play with. My current plotter is a Raymarine 420 and while good at acquiring, I don't plan on investing in cartridges for it.