They had a perfectly working search box in Windows 7, then gutted it and made it search the web whenever you wanted to launch Notepad.
The idea of an indexing service is good though. KDE's Baloo faces similar issues. It's not that easy to make it a good experience.
Everything (mentioned in this thread) comes closest to being fast, reliable, and usable. It can even index external disks and search them while offline.
For some reason its accuracy has dropped in recent years but in the Tiger days it was really good.
How else would they trick you into opening and using Edge, the best web browser in the whole wide world?
/s