A slightly late reply, I'm only just half way through Hell Awakened, but I wanted to make a couple of observations:
Hell Awakened has - up until MAP 15, and including the two secret maps - been entirely playable and not more than "very tough" on UV with fast monsters. I realise different people will find it difficult at different points, but I would argue that it is broadly well paced even at this fairly brutal difficulty.
However there is a jumping challenge over void in a map that I can't remember off hand. The area is surrounded by cacos and imps, there's some tall poles that one has to jump over to get to a blue armour and teleporter back out. Said "poles" are spaced in such a way that makes it almost impossible to do without clearing out the monsters. Even then I just couldn't do it, and I'm fairly dexterous.
But worse, and so far the only major complaint I have with this map pack, is the end of MAP15 with the "corridor" to the exit. With the cyberdemon there it simply isn't feasible without invulnerability or dialling down the difficulty. Without him, it would have been entirely possible.
Having said all this, Hell Awakened has been one excellent and memorable experience after another and absolutely everyone should play it. This map author has a knack for creating memorable designs, and there's been a ton of them so far.