I use DJ as well. Its easily the best out there.
However, it is written in java (poorly, I gather) and is a memory hog, so if you don't have plenty of RAM and a decent processor, you'll probably have the same experience as the Grump. However, there is a ton of free user art available (and more everyday as that community is expanding - and in truth there is more free user art available than commercial art), and the revised license allows for commercial use of DJ maps when not using Fluid's art (or other copywritten art, like the cartoony SKG pack).
My biggest complaint about DJ is that the initial map size is fixed, and that is just poor design. Happily, they added a function (likely a hack) to let you change the scale of the map, so its not as limited as it used to be - but to do a truly large scale map, you still need to do multiple maps and make sure the edges align properly.
I love putting WWG terrain on my DJ created maps. Makes for a really impressive gaming board.
