My experiences from testing 2.6-alpha0:
For some reason, the GTK3-client's UI was derping around (buttons and stuff weren't draw, but instead shown as unicolored fields), so I switched to GTK2 again.
There I noticed that the "Unit: Orders / Goto events" event also triggered when trying to move a unit onto non-native terrain with the default numpad keys. Of course this is somewhat logical, but at the same time it's annoying: either I get an unneeded message every time I press the wrong button or try to move my ship straight into one direction when it hits a continent, or I don't get messages at all if a goto order fail. Should be split up into two events that can be configured seperately IMO.
Also, the supplied "hexemplio" tileset has some glitchy graphics (for example cities) ─ I suggest including GriffonSpade
tileset instead, since that's basically the same, except most of the adjusting, offsetting and editing work is already done.