Some more outdoor variety would be great. Like small lakes/ponds or actual rivers that are more than a few feet wide, bridges, stuff like that.
First, thanks for posting these screenies. I've been looking for something like this for ages! I don't really understand how WotC expects me to buy these sets without knowing what's in them...
Still, despite that I _have_ bought two sets: DT4 and DT5.
DT4 is excellent and I think, I've used it in every session since I got it. Since most of the action in my games happens in the outdoors, I could use a lot more of these: Rivers and Bridges, swampy terrain, snow & ice, mountaineous areas, city terrain, etc.
DT5 was a major disappointment. I've been fiddling with the pieces for hours (before using them in a game) and came to the conclusion that I'll probably never use them. Too many small pieces and simply not enough ways to combine them correctly. The black borders kill every utility they might have had.
Maybe, I'll design a dungeon at some time in the future using these things, so I'll at least get to use them in the game _once_.
I don't see much advantage in actual _dungeon_ tiles, to be honest. A dry-erase battlemat is much more useful for that.