I've been working on an Isomectric Engine for the last few days. It shows off a few of the things BYOND Isometrics are capable of.
A few problems I personally encountered while making this engine are that BYONDs Map Maker is not designed for isometric maps. Creating the map with varying elevations was tricky at first, until I figured that if you count down from the top of the tile, you can reach the bottom, assuming you know the elevation and offsets.
Also, the Pixmap editor is also designed for tiled icons, which can get a tad bit annoying at times. But that's trivial.
The main issue I had was the math. I'm not good at math at all, but all things considered, it turned out pretty good.
Check it out: http://www.byond.com/developer/F0lak/IsometricEngine