Lion is a great OS. It has brought many great user features (Versions, autosave etc) and many fantastic developer features (Autolayout, popovers etc). It has brought one new feature though that is annoying a lot of users: Mission Control. I've mentioned some complaints I've got about it on twitter, but it's got to the point where I really need a blog post to convey my full opinion on it. I can't quite remember another change in an OS X update that was so big, yet so awful.
For those who don't know, Mission Control is a sort of replacement for Exposé and Spaces that tries to combine the two, along with full screen apps, into one central location for managing windows. It sounds good in theory, but as we'll see the reality isn't great.
What I like
It isn't all bad and there are some things that I like. Firstly, you now have a different desktop background per space, which is a nice change. The Mission Control UI is also prettier than the old "All Spaces" view in Snow Leopard. And probably the best change is that you can create and delete spaces from within Mission Control, removing the trip to System Preferences.
The problem is, that's pretty much all I can find good about it. So what about the bad?
What I hate, but can turn off
By default Mission Control makes Dashboard a space to the left of your first space. It sounds nice at first, but you soon realise that it's a lot more work. Pressing an F-key anywhere is easy, but having to flick several times to the left, or bring up mission control, move the cursor to dashboard and click quickly becomes tedious. Thankfully you can turn this off.
The other annoying feature that can be turned off is having spaces re-arrange based on your last use. I can sort of see this being useful to some people, but I often end up losing where things are with it turned on, and if I need that sort of functionality I can use cmd-tab which feels a lot more natural.
What I hate and can't turn off
You might as well get comfy as this is a big list. I'm splitting it up into the 3 areas Mission Control encapsulates:
I have long been a user of virtual desktops. I used Desktop Manager on Panther and Tiger and since Leopard I've been a big fan of Spaces. I usually had 4 spaces laid out. Space 1 was general stuff such as iChat, Skype, NewsLife, Mail and usually Safari. Space 2 had Photoshop assigned to it. Space 3 was for web development and Space 4 was for Mac development and had Xcode assigned to it. I could easily flick through these 4 spaces and had a good spacial awareness of where everything was on my computer. I could easily switch from Space 4 to Space 1 and back with a flick on my mouse. I also had iTunes assigned to all spaces so I could control my music from any space.
Sadly this system that I've been more than happy with for getting on 7 years has been completely destroyed with Lion. Spaces no longer loop round, from the last to the first. This has effectively limited the number of useful spaces I can have. I used to have 4, now I can only manage 2 and have to do a lot of manual re-arranging. I might just be able to manage 3 but it's felt awkward when I have. (rdar://9592853)
While you can still assign windows to certain spaces, or all spaces, this is incredibly buggy in 10.7. Whenever you restart your machine, it forgets them and so you have to reset all your assignments. (rdar://9592870)
There is a lot of gratuitous animation and graphics in Lion. It's ironic then that they actually moved one of the nicest bits of animation from Snow Leopard. With iTunes assigned to all spaces, when I switched space it would stay put, while the other windows slid away. In Lion, any apps assigned to all desktops slide out with the current space and then just appear on the new space. It feels tacked on. (rdar://9844274)
If you have multiple monitors, you may not always have them turned on. I often have times I turn on my iMac but not my second display to do something, but occasionally I need to access a window that I left on the second display. This was easy pre-Lion. I hit F8 to bring up the All Spaces view and saw all the spaces for both monitors on my main display. I could then drag a window from one display to another. This is completely gone in Lion. Firstly it shows windows on the display they were on, rather than on a single display. Secondly, you cannot drag a window from one display to another in Mission Control. (rdar://9844324)
It's so bloody slow. When you switch a space, you have to wait for the movement animation to stop and for the desktop icons to fade back in, before you can move in the opposite direction and the delay between the movement stopping and icons fading in is relatively massive. (rdar://9844555)
You cannot use the Exposé All Windows mode across all spaces in Mission Control as you could in Snow Leopard. This means there's no way to truly see all windows on the system. Instead you have to go into Mission Control on on space, then switch to the next space and the next. (rdar://9844318)
Windows are stacked with the recent most one first. Given how much ridicule was given to Windows Vista's 3D stacked window chooser in terms of usability over Exposé, it's disheartening to see Apple falling for exactly the same mistakes in Lion. (rdar://9844311)
You can no longer click and hold on an app's dock icon to go into the App Windows Exposé mode either. I didn't actually realise how much I used this until I found it was gone in Lion. (rdar://9844305)
And finally we have full screen apps. For laptops these are fantastic, but if when you get onto larger displays and especially multi-display setups, it completely falls apart in its usefulness. Secondary displays are largely useless in full screen apps. Sure you can have certain windows such as inspectors on a second display, but that's more a cop out than anything.
You should ideally be able to make an app go full screen on a particular display. This could be as simple as press and hold on the full screen button to bring up a list of displays. (rdar://9817280) You should also be able to loop displays individual when you're in full screen apps. This would allow you to have a main app on the primary display and several apps on secondary displays which you can loop through individually. (rdar://9817307)
Finally, on big displays it just feels wrong to have the toolbar at the top of the screen in full screen. It feels more like it should be on the bottom, especially with Safari. (rdar://9817332)
Overall, Mission Control is a mess. It has nobel aims, but it feels like it was built by someone who'd only ever had a cursory glance at Spaces and Exposé and who hadn't used any Mac other than a MacBook Air with no secondary display. I seems too complex a system to appeal to regular users, but too awkward a system to appeal to power users. I'm incredibly happy with most of Lion, and can avoid most of the bits I don't like. But Mission Control is both unavoidable and the one bit of Lion I wish I could revert back to how it worked in 10.6. Hopefully Apple fixes at least some of the huge array of flaws in upcoming Lion updates.