I think it looks fine on my 15 inch late 2009 MBP
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I've also got it running on a mid 2010 imac 21
and
on a mac mini late 2012
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very stable
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no issues so far
Mine's a bit younger, a late 2009 MacBook. But it looks great here Sometimes the font in the menu bar is a bit thin but I've only been 'annoyed' by it when it's late and I'm tired. And I'm used to have everything ridiculously zoomed in so it's probably just me. But for me it looks perfectly fine, no weird pixel stuff or anything. And I'm guessing we have the same screen
But overall and with everything very very happy with Yosemite