The eye candy Mac OS X provides you with isn't distracting nor (dis)functional, but it offers you with a good-looking work environment with some serious power underneath the keyboard.
The disk speed is quite regular, as is the perceived CPU speed, but since I loaded my TiBook with 1 Gig of RAM, and the (virtual) memory management is up to par with Linux'es, I can open up plenty of apps without the system feeling slow.
Entering the Switchers world, one has to become familiar again with the shareware software distribution model, since quite a few of the must-have tools are one-man-shop endeavors which require you to pony up some dollars to have a fully functional registered copy. So far, I subsidized Ranchero Software (NetNewsWire), BareBones (TextWrangler) and IndigoField (Proteus). I don't mind spending money of software, especially this class of tools. It's the kinda stuff you don't want to write yourself, that you however still expect to port any feature you might possibly dream of, and for which there exists no services-for-pay business model. Quite different from the open source business model, where infrastructure-class products are shipped for free, but the author expects to make some money on the services for installation, support, or customization.
Welcome to the Fellowship of Switchers! Do try LaunchBar, and for Linux connectivity iTerm is great - both viw www.versiontracker.com
I started looking at versiontracker.com, but nowadays tend to go to http://macupdate.com/
The commercial drive behind versiontracker pushed me away a bit.
If you like opensource software, do try fink (http://fink.sf.net) and install Apple's X11 server. You'll have most of the familiar linux applications up and running in no time. Congratulations with the new hardware :).