why did you choose isomorphic over a top-down view?
It looks interesting, though.
I had made a RPG mapping/gaming thing in flash WAY back in the day, and had always thought about making it into a web version. Never got around to it, though.
All of the top-down approaches just look ugly to me. You're either looking at the top of people heads, or tokens of disembodied heads. This also gives it a pseudo-3d look, with a bit of clutter to add that homey tabletop atmosphere.
I came to the opposite conclusion. When you add perspective to game visualizations, it becomes harder to judge distances, estimate angles, make out details, and identify borders. Small items tend to get reduced to squint-inducing shapes. Large items occlude each other and cause an infuriating visibility problem. The only advantage is that it looks a little bit more like a "real" world, but if you're using a simplified art style, it doesn't matter anyway.
From a UX standpoint, the best balance is "iconic" perspective - most things rendered flat with low occlusion, like an Egyptian painting, much of medieval art, or Japanese woodblock prints. All the boundaries can remain clearly delineated with this style, but aesthetics can be retained through careful composition of each icon.
I did exactly this style for the game I'm working on. My reference points(within video games) are Ultima 1-5, Heroes of Might and Magic, and Battle for Wesnoth. In these games you are never wondering what something is, because you can always make out what it looks like.
Normally I'd agree with you, for those exact reasons, and my first prototypes were all generally flat (also being a fan of the Ultima series.)
But when I tried the current isometric style on a whim, it managed to solve all of the problems I was trying to address. Probably because I use a hybrid approach: only the underlying battlemat tiles are isometric. The miniatures are flat, slightly-transparent stand-ups and always face the player.
I had made a RPG mapping/gaming thing in flash WAY back in the day, and had always thought about making it into a web version. Never got around to it, though.
Good luck with yours. =)