Other than my mapping problem, I also think it's definitely on the right lines.
I think the use of java giving easy install and multiple operating systems is a great idea. The wizard configuration to set it up is good too. I also loved the way it just worked with both my TNC and aprs-is without any messing around. When I tried it, messaging worked well as did query.
My map issue is probably related to the sea not being coloured but rather having the same colour as the generic map background. The same maps displayed (from online sources rather than precompiled) in SARTrack and AGWTracker look just fine. I'd like to be able to delete all the objects in one go -- so as to remove them from my map -- but that's a local problem related to the transmission of "duff" objects around here. I also like to be able to get more information about a source (station or object) by clicking on it or something rather than opening the station list and hunting for it. And I don't understand why it downloads 638 fonts every time I start it (according to the preferences tab)!
But it's still a beta and being improved on a regular basis! So all these things will come if people ask for them. It's definitely a product to use if you can.