• Spotlight – With a quick keyboard shortcut (Cmd+Space) I can launch apps by typing the first few letters of their name. I’m sure there’s similar things on other OSes but I like that this is built in and zero-config.
• Applications/Installations – Most apps (apart from chunky stuff like CS3) are installed by just dropping them in “/Applications”. It’s a refreshing change. The lack of a registry is also nice. Sure, there’s files that occasionally need hunting, but it’s less of a hedge maze.
• Icons – Icons are waaaay easier to apply to folders and apps, since apps are actually folders in disguise. Especially with Img2icns.
• Scripting – AppleScript and other Unix-based scripting make it really easy to automate stuff, especially for a programmer like me. Seriously, AppleScript is underrated as a quick and dirty automation tool.
• Eye Candy – Haughty people might say they don’t need frivolous things like eye candy, but damnit, we spend our lives in front of these things, so it might as well look decent, instead of the hodge-podge of visual effects that windows has. And the focus on ‘eye candy’ has also streamlined a lot of usability situations. On the whole OS X has a sort of smooth feel to it, which is sometimes very comforting :)

Some favourite apps of mine so far:

• YummyFTP – My FTP app on the windows side is FileZilla, because I like the dual browsing. YummyFTP has this plus a bunch of other nice small features, for example supporting local file/folder label colours. A milestone as my first app purchase on this thing :P
• Img2icns – Easy quick conversion of images to a variety of icons. Nice visual appearance and drag-and-drop. Free, but I’m tempted to buy the full version.
• iTunes – It actually works nice and integrated, compared to the PC version. Yes I know I know, it’s just an iPod/iPhone accessory, but it works nice and fairly simply for me, and running it on it’s native OS is nicer than a PC port.
• GliderPRO – If you have used a mac and have not played this game on it at least once, I weep for you. I installed BasiliskII on my PC years ago just so I could use the level editor (the editor is OS 9 only, sadly)

So yeah, I’m liking it so far. The only downsides is of course the cross-platform compatability and old Windows apps I can’t quite yet use (like the Steam version of Braid :O ). Now I just need to make sure I pay back my boss, who kindly bought this MacBook for me :)