I use it all the time. Emails and docs in particular. I have emails in a zillion folders over the past 10 years and lord knows I often am looking for a message or thread when I can't remember the person's name. It is GREAT for this type of thing (I don't know who it was, but we emailed about "XYZ" so I search on "XYZ" and bam, there he is). Docs too - I am experimenting with dumping almost all my new docs in one disorganized folder and it is working out, though the anal retentive part of me has a real hard time with this - it is agony knowing those files are unfiled!!! Sorry, I have to go wash my hands now, it has been over 20 minutes.
Scottfab, with all respect to you, it isn't really about laziness, it is about efficiency for *certain* tasks. There is a method of measuring the efficiency of a UI to perform different tasks called GOMS. In a GOMS analysis each step or action is given a time value (keystroke, click, move cursor, select menu item, drag...). Comparing different approaches to some task can reveal which is more efficient. In fact, a famous GOMS analysis pitted the one button Mac mouse + Mac GUI (OS 7 or 8 or so) against the two button Windows approach and the Mac won out in most tasks. Any way, if I did a GOMS on my "can't remember the name of the guy in an email 4 years ago" scenario, Spotlight wins hands down over the finder or Mail even though I think I have a pretty good filing system for my mail files. Even so, I'm sure we do different things and are different people with different preferences. You may know where all your stuff is, but maybe at a high cost of time and effort in filing. Heck, you may be a natural librarian! Even so, its your computer and it should let you do anything you want to and give us all options.
By the way, of course I still do use the finder to get things where I know or am pretty sure of where they are, though I use XMenu to make it even more efficient, but even without XMenu the finder would still be a better choice for those types of tasks than Spotlight. I'd never use Spotlight to launch an app!
What's great about Spotlight is it now gives the Mac nearly equally powerful options for searching or browsing and the option to choose whichever fits the task at hand. P.S. Default keyboard shortcut for Spotlight is Command-Space - very easy.