I’m still using a fair amount of vintage PowerPC Macs and older iOS devices on a daily basis. I’m writing this on a 17-inch PowerBook G4 from 2003/2004, running Mac OS X 10.5.8 Leopard. I also use other Macs running Tiger (10.4) and even Panther (10.3). I’ve been using these Macs and these versions of Mac OS X constantly for years — and in the case of an iBook G3 and the 12-inch PowerBook G4, since their introduction, April 2005 for Tiger, October 2007 for Leopard. While I indeed encountered a few annoying bugs when Tiger and Leopard were in active development, I remember how the most egregious usually disappeared after a minor OS X release (I even remember resolving an issue on one of my Macs by downloading a Combo Update and reinstalling).
Whether small or a bit more serious, the bugs, then, felt like something transient passing through an otherwise rock-solid environment. In my 10+ years of using these PowerPC Macs running Tiger and Leopard, I’ve never encountered new issues or noticed things I didn’t before, and I’ve had plenty of time to become ‘hyper-sensitive’ to how they work. Sure, the PowerPC platform isn’t in active development anymore, and I’m speaking of machines and systems that are basically crystallised in their most mature state. But still, in all these years of use, with all the first-party and third-party software I’ve thrown at them, I should have been able to encounter bugs I’d previously missed, or trigger unexpected behaviours.
It’s hard for me to speak about the buggy-ness of Apple’s software these days — I just don’t experience the sheer number of irritating, daily annoyances that others seem to. But I can say without hesitation that Apple’s software during the days of Tiger and Leopard was rock solid.