I won't deny it, I'm a pretty hard core warhammer 40K player.
So when I build peices, I've learned to focus on both functional and look.

The 4 Cathedral pieces have been a huge hit so far with all my friends that come over to play. Eventually I'll see how them handle a road trip to someone elses table.

They provide excellent line of sight blocking, which really shakes up a lot of players cause they are use to more open terrain pieces.
Only issue that we've had with them, was easily handled, and that's the roof and tops of the bell towers present problems. The roof pieces are slanted way to much for putting models on. The Bell towers would be 3 or 4 levels in height. We've simply declared those areas as impassible terrain, to prevent attempting to place models there.

Another that I've incorporated is the fact that I purposely build the height difference between levels heighter than "rule books" suggest, and thats because, hands fit into them better. The standard is considered 3", and I will use 4, to 4.5" between levels just for that reason.