We use a combination of stock textures and some custom ones that still mesh well together, so this may be why some textures may appear lower res.
The Black Parade isn't compatible with graphics mods. The campaign was not designed with any of them in mind. You can still use them if you want but you'd have to do it manually.
It's a nice fun mission to play on one's lunch break, but that's all. I wish there was something more than "get down as fast as you can without dying" to this level. A few additional obstacles (such as archers) or hidden nooks and crannies with loot would make it more enjoyable and challenging.
I played It for the first time a while ago and I found It to not be that good. It looks pretty, but I felt the gameplay to be rather drab.
Keep in mind that the original has more votes as well, so that may influence the higher score.
I'd recommend trying it out when you can, make sure to give it some stars to raise the score, if you like the FM that is.