I made a default upgrade, and there were no problems although the iMac had lots of additional software installed (including system utilities etc.). Everything is running as smoothly as can be wished.

I read a lot of complaints about the details of Leopard from the net discussions. A bunch of nitpicking ninnies! Although Leopard is markedly different, I think the new features (transparent dock and stacks) are real improvements, not just eye candy.

I haven't yet tested Time Machine, but will do this in a few days. I'm currently doing the backups with Carbon Copy Cloner, this is sufficient for now.

The value of the new features remains to be seen. Quick Look, Spaces etc. seem reasonable improvements, although not revolutionary. I already got used to Quick Look, and probably will miss it on those Macs running Tiger. Also, some of the current software requires Leopard to work properly, for example EyeTV and Cover Sutra. Thus it was time to make the leap to Leopard.