That's the first time I'd seen that one. I'd been doing a lot of expermenting with GanttProject which at least from a appearance perspective looks better
Yeah, GanttProject was the one we thought of merging with; they obviously had a far prettier GUI, and (at the time) easier to use, whereas our effort had all gone into backend data structures and special features (like zooming) etc. It's paid off now with the ease with which we can add new features (the last time I looked at GP's source it was ... ahem ... chaotic), and also the fact that we've completely re-done the GUI, yet had to make almost no changes at all to the data structures.
In particular, GP also has internationalized text, which is very nice for many people, but it does still have quite a poor UI. After the previous Ganttlet UI evolved into a horrible monster
over successive versions, the new version aims much more for being "totally intuitive yet extremely powerful" (but you'll have to wait a while before all the features are implemented in the UI...).
(and if anyone has enough spare time, we could still merge with GP anyway, and hopefully end up with the best of both worlds?)