I signed up for the OS X Yosemite public beta the day Apple opened it up, back in late July, and I've been running it for about three weeks now on my old 2012 MacBook Air (not my main machine, because I'm not an idiot, or at least not that kind of idiot). Figured it was time to actually write down what's true versus what the tech blogs were hyperventilating about back at WWDC in June.
The design change is the thing everyone talks about first, and yeah, it's a lot. Flatter icons, translucent menu bars, that new frosted-glass look on the Dock. Mostly I like it. But the system font switched to Helvetica Neue and at small sizes, menu bar text, some sidebar labels, it genuinely gets harder to read. I'm not imagining this. I bumped my display scaling down a notch just to compensate and it still looks a little thin and grey to me, especially with my desk lamp at the angle it's at in the evening. Somebody at Apple apparently thought this was fine on a retina display in a bright room and didn't think as hard about the rest of us squinting at 11pm.
Spotlight is the feature I didn't expect to care about and now use constantly. Hit command-space and instead of a little dropdown in the corner you get this big centered search box that does calculator math, dictionary lookups, Wikipedia snippets, unit conversions, even a mini Maps preview. I looked up "14 stone in pounds" for a British recipe conversion the other night and it just answered inline, no browser tab required. Small thing, saves actual time, every day.
Notification Center got a "Today" view tacked onto it, basically a widget dashboard, weather, stocks, a calendar agenda strip. It's fine. I added the World Clock widget because a friend moved to Berlin and I got tired of doing the math in my head, and that's about the extent of my enthusiasm for it. Doesn't feel essential yet, feels like Apple copying the iOS Today view because it existed and they had the code lying around.
Here's my actual complaint, and it's not a small one: Handoff, the feature Apple spent half the WWDC keynote demoing, start an email on your Mac, finish it on your phone, is basically unusable right now, because it needs iOS 8, and iOS 8 isn't out yet. It's sitting there in System Preferences with a toggle I can flip, connected to nothing. So the marquee cross-device feature of this entire release is vaporware on my end until whatever iPhone event Apple does in September actually happens and I update my phone. Kind of a weird thing to lead a keynote with.
iCloud Drive is also in beta-of-a-beta territory. I turned it on, regretted it a little, some files took forever to actually show up synced, and I've since mostly gone back to just using Dropbox for anything I actually need reliably. Maybe it'll be solid by the real release. Maybe not. I'm not betting my thesis drafts on it either way.
Stability-wise it's a beta, so obviously things crash, Mail.app has beachballed on me twice this week for no reason I can identify, and once Preview just quietly closed itself while I had a PDF open. Nothing that's lost me work, just enough that I wouldn't put this on a machine I depend on for anything real. Which is exactly why it's on the Air and not the machine I actually write on.
Unrelated, but everyone in my Twitter feed this week is either dumping a bucket of ice water on their head for ALS or nominating three more people to do it, including, apparently, half of Silicon Valley. My cat watched me debate whether to do mine in the kitchen sink or just wait until someone forces the issue, and honestly the jury's still out on which is worse for my dignity.
If you want to try the beta yourself it's free through the AppleSeed program, sign up on Apple's site, back up first with Time Machine or Carbon Copy Cloner before you install anything, and do not, under any circumstances, put it on the computer you need for work tomorrow morning. Ask me how I know some of this from three years of doing exactly the opposite.