Ubuntu on MacBook Pro - pros and cons?

It can be done. I'd take a look at the Apple Users sub-forum on ubuntuforums.org for in-depth details.

These are also two good starting points for info: 1, 2.

Also check out which model MacBook it would be. For example I have a crappy plastic one that's a couple of years old. Runs like a trooper. It's designated '5,2'. The model type will be important in determining what needs to be done to get things working.

PRO

• Lovely hardware.
• Flexibility of GNU/Linux.

CON

• Things like special function keys won't work out-of-the-box.
• Battery life will be significantly lower [citation needed].
• A generally less integrated experience (e.g. I notice that Thunderbolt and WLAN aren't working yet with Natty and the latest offering of MacBook Pros).
• Hibernate and suspend tend to be a bit iffy.
• You're getting rid of what is, in my opinion, a pretty good OS. If you need the *nix aspect of Linux it's all there. If you want something like the repository system you have options available too.

My idea would be to set-up a dual-boot environment.

Unless you're considering buying a very old Mac notebook, you needn't worry about the PowerPC architecture.

Playing DVDs is easily done. I've never had much fun with 64-bit Flash. Google Chrome arguably works better in Ubuntu.

Hope this helps.