The love story is a little weak, yeah, so if you were to strip it out, it wouldn't hurt things too much. The only element the love story adds is Quinn, who can be a big help in the final battle--since the module takes place over the course of one night, the PCs might need all the help they can get by the time they reach the cold rider.
You'll want to watch the resources of the PCs for this module, as, like I said, it takes place over a single night. No time to rest, no time to regain spells. And there's lots of fey that can inflict permanent to semipermanant status effects on PCs; there's a nymph who can blind them and the frosty chiselers have their brittlebones curse. The nymph queen who gives the PCs their deus ex machina potions might also want to throw in some potions of remove curse and remove blindness/deafness.
The dark ice fey is a neat template, but the dark ice brownies aren't such a good utilization of the same. They've got 1 HD but a ton of SLAs, which makes them wibbly on the CR front. If a PC gets in a solid hit, the dark ice brownie is dead, but if not, confusion and glitterdust can make fights go on for a lot longer.
The Tent of Modern Industry is really cool, but rather unfortunately implemented. As written, the grimstalker, which is capable of bull's rushing PCs around and throwing them into the murderous machinery, is outside, while weak dark ice brownies wait inside. I think it'd be a good idea to switch 'em (and that makes the illustration fit much better, if you're the kind of DM who shows his players the pictures).
Make sure your PCs know all of the attractions at the fair, so that they have as much fun as possible before things start going down. My description sort of glossed over the freakshow and the brothel-tent, and so they wandered in the other direction and didn't get to experience those areas before the cold rider descended.
As written, all of the freaks die or flee when the carnival takes a turn for the worse, but that doesn't seem nearly as fun to me. Perhaps the pinhead grimlocks are let loose to indulge in their violent urges? Perhaps Prig steals the homunculus-in-a-jar and balances it on his head during the chase, slowing him down as he shows off?
And lastly, if I may do a little blatant self-promotion, my Pathfinder Bestiary thread has in it
twigjacks, evil fey which would fit in nicely, both in terms of flavor (they live in deep woods and murder lumberjacks) and in CR (3).
Hope this all helps!
