Yep - the splashscreen for Ubuntu ppc is a major drag - need to pass the “nosplash” kernel parameter at the yaboot boot prompt. But onwards with openSUSE!
I read somewhere that opensuse will automatically create a partition for itself alongside OS X. Obviously i don’t want the hassle of having to reinstall OS X, so comformation this actually works would be great.
Dual-booting is entirely possible. The only thing you’ll need to do is make free space for it. That means either resizing your existing osx partition, or reinstalling and using osx’s disk utility to repartition it - say half and half first.
There are some instructions about for resizing your existing hfs partition, or you can use a commercial product like iPartition to get the job done. When I do it, I just reinstall osx, have the combo-updates handy and go for it. Makes for kind of a long install session however. 
Once OSX has had it’s partition resized, or you did a reinstall to say half the disk, just let openSUSE’s installer install to the “free space” automatically. Also, openSuse’s installer will automatically take care of making sure that the special apple partitions that are needed beyond the usual root and swap are taken care of.
Are there any known issues with iBooks in particular? Mine is a G4 1.2Ghz, 1.25 RAM… errm… ATi something or other.
You’ll just have to find out - although don’t be surprised if you have to manually edit your /etc/X11/xorg.conf file, since Apple hardware isn’t exactly chatty with linux installers - but I’m sure that opensuse’s installer will give it it’s best shot. For my G5 iMac, no sweat - although that machine never had an installation issue with video.
The nice thing that I found with openSUSE on ppc is that they still provided a fully-populated xorg.conf file, unlike other distros that provide a very minimal or even empty file. This makes it hard for someone new to xorg.conf editing to not even have a template to play around with. Nice of openSUSE to provide that!
Does OpenSuse perform better than OS X on Mac Hardware?
Depends on what you want it to do. Flash and 3D are problematic just basically due to vendors not compiling or supporting the ppc architecture for a few years. Flash alternatives like gnash and swfdec exist, and they do their best, but if you are looking for an osx replacement - perhaps not.
And… finally, is OpenSUSE really hard to adapt to?
No more so that Debian or Ubuntu or Fedora or Gentoo.
I ask because i’m a debian dude. only ever installed and used Debian based (mainly Ubuntu, xandros on my eeepc and knoppix is my backup livecd for fixing shiz.)
Then you should have no problem. Instead of apt-get, zypper works just fine if you are used to the cli-way of doing things.
I had a very nice install of 11.1 on my G5 iMac, although I couldn’t get sound to work, but it wasn’t a showstopper. The only thing that tripped me up initially was the repo having to be
powerpc.opensuse.org
during my netinstall.
I’d say go for it!