Rubbish...
Leopard is absolutely great now! With 10.5.4 it's very stable - I'd say at least as stable as Tiger. In other words, it's so stable you'll never have a problem with it unless you're really doing weird stuff with it.
In most cases Macs see an
increase in performance, which isn't what you'd expect from a new OS, naturally. Just look at Vista. But Leopard is fantastic.
1GB RAM is absolutely fine for Leopard too. My iMac only has 1GB and it's rockin'. With all the new features and performance upgrades, I'd say it's definitely worth jumping on the Leopard train. Snow Leopard won't look much different, and will probably be out shortly after the new year, say February or something.
Also in my opinion, the old style of Mac OS (the pin-stripes, the 2D Dock, the brushed metal) is really looking out of fashion, if that matters to you. I know they say Leopard's new look was to compete directly with Vista's, but I think it looks wonderful. Less stressful on the eyes too (darker tones, less glaring).
P.S. I never thought the jumping action of the icons looked right on the old Dock... Now it makes sense because they're jumping off the '3D tray' instead of out the 2D box.