It's excellent. I like it a lot. Leopard is a worthy upgrade. But you can read all about the good stuff elsewhere; I'll just list my complaints...
An unknon percentage of MBPs have been affected by a squeaky spacebar... inluding mine. Right on the spot where my right thumb hits the key. The keyboard is otherwise nice to use and key presses have a good feel.
The screen doesn't tilt back far enough. The screen is better than the glossy screen of the MacBook, but colours still change a little when looking down from above. Noticeably, the drop shadow on the active window turns from grey to white. I find myself wishing I was shorter, as I'm not always looking at the screen from the best angle.
The Wi-Fi/networking implementation is screwy. It thinks the wireless LAN at work is encrypted with WEP or WPA (it's not), and it either won't connect automatically, or it will connect and choose its own IP address, instead of authenticating like it had been told. Grrr.
Fetchmail wants to deliver email to localhost:25, but there is no longer a mail server running, and with Leopard being comparitively new, I've not yet found good information on enabling one. Interestingly, when I was playing with this the other day, localhost resolved to some uknown SMTP server's IP address and fetchmail was trying to give my mail away...
Time Machine seems to be just what the doctor ordered, but not exactly what I want. Since I already do a full disk backup with SuperDuper, what I really want is to select a few folders for backup by Time Machine, instead of backing up everything and choosing folders to exclude.
Unrelated to Apple, some third party developers need to think harder about their application icons. SuperDuper and YummyFTP, for example, have icons that are harder to pick out, since they are mostly grey and have fine detail that is not clear unless you're looking at a big version. Some of the best icons on my Dock: Opera, Safari, Firefox (vivid colours make it easy to pick out a particular browser); Coda and Transmit (Panic are known for design); iView, CaptureOne, Miro (yes, it looks like an M&M), Adium, TaskPaper and WriteRoom. Hmm, most apps have good icons, actually.
Australian English: grey or gray?