Yes. I bought the Mac Mini when it was first introduced. It was (and is) a fantastic machine. It ws also my first Mac. On the back of my experiences with the Mini I switched over to using Macs exclusively at home (my day job I still use Windows, but I have a choice at home). I pushed the Mini to the limit and ended up getting a Mac Pro, but the Mini was still an excelent first step. A number of friends and family were very impressed and have bough into the Mini too.
I had the chance to use the latest Mini at the new Glasgow Apple store. The move to an Intel processor and a base configuration of 1GB of memory make it far better than my old G4 1.42 GHs model. No surprise that it matches my MacBook - given the two share many of the same components.
As for waiting... If the Mini and iMac had not just been upgraded I would had said wait for sure. But as it has, I doubt we will see another hardware update this year. If you can wait 12 weeks I would say wait. If you want to taste some of that Apple goodness now (with the knowledge that Tiger is now a mature OS with most of the kinks worked out) then go for it.
If it were me - I'd wait.
But then I have all these lovely Apple products to play with in the mean-time