Updated Mavericks to Yosemite couple of nights ago on my mid-09, 6GB, no-SSD MacBook. Absolutely Zero Issues. Like the simpler icons and cleaner fonts. Safari 8 is a little quicker and the old Grey Favorites Bar is finally centered AND LEGIBLE.
I'm glad for you but zero issues for some doesn't mean that Apple did everything well. If some have very serious issues Apple should take care of that, we pay a premium price to avoid issues. I can understand that something goes wrong occasionally, but Apple's silence and apparent disregard about the problem is frustrating to those that can no longer access internet. I think that this would never have happened under Steve Jobs.