I'll grant you that Spotlight could be a bit quicker and smarter, but I nevertheless use it all the time. I was never a Quicksilver power user, but I've found Spotlight adequate enough that I've never bothered installing any alternatives (ie. Launchbar).
I think this is actually the crux of the issue. Some really unique ideas were replaced with "adequate-enough" ones that ultimately had the (unintended?) consequence of killing those other special features. Some may say this is a good thing, but it a phenomenon that exists nevertheless.
