I haven't used OpenCPN, so can't really comment on it, but I've been using Coastal Explorer for about 5 years now, and it has (or maybe I have) graduated from being a companion tool on a laptop to being the primary and only charting and navigation system on my boat. Plus I have a second copy on my laptop for home and portable use. It's by far the best $395 I've ever spent on anything for my boat(s).
What I like, aside from running on a real computer with a mouse and keyboard is:
- Really simple route creation and modification, even while underway and following an active route.
- Works great with autopilots allowing the AP to follow the route you create on CE. CE provides all the ETA info to each waypoint and to the final destination.
- Interfaces well with marine electronics and sensors via either 0183 or N2K. When I last checked OpenCPN did not support N2K, and that was one of the reasons I did not pursue it.
- Truly outstanding support. Rose Point is one of the best in the industry in this respect. And unlike many electronics companies, they take bug reports seriously, investigate them, and actually fix them in a timely manner.
- CE supports one of the broadest selections of charts of any product out there. It supports all the US vector and raster charts, and they download and update automatically. They also support all the C-map charts, and have a really good package of raster and vector charts for the BC, Canada coast (I'm using those now). And they support all of the standard chart formats, so can work with any commercially available electronic chart.