Safari is good, however i had to take that damn metalic look off (
http://homepage.mac.com/farmerjeb/safari.jpg) Safari is so fast because it caches items and then hogs shitloads of ram after you've been using it for a extended period. That is a definate problem with the program.
As for the iApps...
IE sucks anyways, use a mozilla browser
Safari, definatly has potential but lacks tabbs ( a tab is a way of having multiple windows open in the same window if that makes any sense) this is the father of the tabbed revolution
http://multizilla.mozdev.org/Itunes is the best there is, i can never get used to audium, especialy because i'd have to rebuild playlists and it doesn't suport the ipod.
iChat is truely horible, Adium is a much better alternative, its even a tabbed chat app. Its so great to have clutter minimized into one window, especialy when your chatting with 5 or 6 people
Mail, works good, does not work with hotmail or yahoo by default but that can be changed by various opensourced mail proxies out there.
If you want to talk about speed issues... iTunes hangs for a bit when i load my playlists with over 2000 songs on them (i have 4,400 mp3s in total. or 18 days of music
)
What i truely love about osX is the avalible open source software, especialy because apple released X11 and now open office will be perfect replacement for apple works.