I have it and wish I would've bought the Smarcraft tach instead.
The app is very glitchy and doesn't work sometimes. Have to close and restart it before it will connect. The trouble code function is next to useless since Vesselview codes do not correspond to anything in service information. Only a dealer can cross them over to the actual code for troubleshooting. For that purpose it's only one step above useless.
Being able to view temp, oil pressure, RPM, etc. is nice and all but i bought it mostly for trouble codes.
Smartcraft is only a little more expensive than VV, will do all the same stuff, can show the actual code when an issue pops up, works as a traditional tach, and will also allow you to network with these bigger graphs and display all of the engine information on them.
You can also run a standard tach on them just fine, you'll need to tap into the right wire on the Smartcraft connector at the control box.
Vesselview is only compatible with 2004 and newer 40hp+ Mercs. Yamaha and Suzuki have their own setup that is similar to Smartcraft.