In Quicksilver, I was 400 pages in, and couldn't give a fetid dingo's kidney about any of the characters, where they were going, or what the plot was.
In American Gods, Gaiman has me hooked by page 40, and I want to keep turning the page to see where it's going, and what's going to happen next.
I'll probably sell my Quicksilver on eBay (unless a reader here wants to buy it... I treat my books pristinely, as anyone who's borrowed from me -- or had to buy me a new copy of something they tried to return in less than perfect condition -- can vouch for).
I'm about 400 pages into Quicksilver myself and I'm enjoying it. Go figure.
I find as is true with the rest of his novels, you need to tough it out for the first half of the book. The pay off comes around 50 pages from the end.
I love American Gods. Someone got anal about it and has a fan site that has a good chunk of the mythology references listed, if you aren't into googling all them. I can't remember the link, but I think it might be linked off neilgaiman.com. :-)
Shadow is just one cool dude, even after everything that happens to him.