Off the top of my head, talking about the Ubuntu 12.04.1 I use daily on two different Thinkpads:

I have to log in and out or reboot pretty much every day to solve X or window manager problems. There are a variety of focus and window ordering issues. Coming back from sleep each one has different display twitches; nothing worse than the usual Linux user contempt, but definitely unpolished. The Unity stuff is going in a good direction but I don't think they've been doing a ton of user testing; it also frequently feels clunky to me. Network Manager is slow to find networks and regularly crashes. Device support is so-so: the Android tethering that is support to magically work never does; plugging in a phone or a tablet frequently requires command-line incantations and is often buggy. One of my devices has a touch-screen; a minor kernel upgrade broke this a couple months back, and it is still broken.

I think they're right to go for a better UI experience, but right now I think they're in a valley between the solid but ugly Linux experience I was used to and the solid but friendly experience that Apple has inspired them to pursue. Right now I think it's flaky both in a usability sense and in a technical sense, which I find thoroughly disappointing.

>I have to log in and out or reboot pretty much every day to solve X or window manager problems. There are a variety of focus and window ordering issues.

These aren't specific. I honestly don't know what you're talking about here. I've logged out of X to solve a problem once - that was checking "Use the NVIDIA driver" and then rebooting. The only time I've ever rebooted to "fix" an "X problem". That having been said, I won't defend compiz for a second. That was a mistake and they're sinking more and more money into it to my disappointment.

>Device support is so-so: the Android tethering that is support to magically work never does

My Galaxy Nexus, Droid 1, Nexus 4 and Nexus 7 3g - I tap USB tether and about 5 seconds later Ubuntu tells me it's connected. (Unless this has regressed in 12.10, I haven't had reason to use it lately.)

>Network Manager is slow to find networks and regularly crashes.

You can get NM to crash? I hope you've filed a bug report because that is a major issue.

As long as we're talking about things that make me crazy about Linux, here's another fine example.

You asked a question. I took some time to give you an answer. Did you thank me? Did you acknowledge the information as relevant? Did you ask follow-up questions to better understand the situation? No, no, and no.

Instead, you seize upon the parts you can most easily argue with. You use scare quotes to imply that I must be an idiot. And you tell me what work you think I should be doing.

It's not my job to educate you. It's not my job to convince you of things you don't want to believe. It's not my job to file the particular bug reports you think best.

Your behavior here exemplifies the arrogant, self-centered, argumentative idiocy that has repeatedly driven me away from participating in open-source projects. I've got better things to do than to fight with people on the internet. Especially anonymous ones.

X is pretty weird sometimes, you switch displays, or suddenly connect a third display, the only way to fix it is to reboot X. Sometimes it works, and sometimes it doesn't. I honestly don't know X well enough to debug the problem, so restarting X is just the faster solution. I'm guessing you probably don't us X on the road as much, I feel like this is a normal thing for me -- restart X to solve problem with weird display.

Ah, if "on the road" means plugging and unplugging external monitors, you've caught me in my "oh I should have thought of that" spot.

I haven't had to do that in a long while. I have a permanent desktop machine so my laptop is only for at coffee shops or working at a friend's place. I can certainly understand how hotplugging can be a disaster. Thankfully, I have noticed an improvement with that with Nvidia's more recent driver releases, even possibly as late as the ones resulting from their work with Steam.

Anyway, I've been running Wayland builds on and off for a month now, let's hope that paves the way for minimizing these problems even further.

You never have to plug in your laptop to do presentations or anything? I feel like I do that all the time... plus you never know what type of lcd projector they are using. Sometimes a guy comes and tries to help you, but when they notice you're running linux they sort of back off.

Are you using a proprietary graphics driver? With Intel graphics, none of these problems seem to pop up.