Did a lot of playing around with this last night and it works quite excellently.
A word of caution: 256x256 maps take a very long time in between turns, and I am running Win7 64-bit with 4gb RAM. I am sure that when Stardock releases the 64-bit client, this will be improved upon. 192x192 is very quick, however.
One thing that I would like to see is a toggle for mountain ranges vs. sporadic mountains. As it is now, they seem to be very sporadic, and do not chain together as much as I would expect.
The same type of toggle would be nice for the shore types.
As someone mentioned earlier, the random seed would be nice to have access to (and to be able to type in) so we can come back to maps that we like that we may want to tweak a bit with the sliders.
Of course, I could live without all of these things, as this program works beautifully as is.