Gaming pretty much, and if I wasn't a fiddler that'd be about it.
I've been running Mint Mate or whatever was before it for two years I guess daily now, and I work online for a living. It's really, really good. I used to run Ubuntu, can't stand that new interface at all. Mate is a better windows than windows.
Or untill I want to move to an SSD and can't run any of the cool software like Samsung has.
And have to jerk around to enable TRIM, and possibly the 20 other things people say I need to change to keep an SSD happy in Linux.
Or I want to run some good hardware monitoring software, LM-Sensors and the Gnome panel app are OK but very limited and barebones. My Sabertooth 990FX has a crap ton of hardware monitoring options, it's one of the reasons I bought the thing, and they are wasted in Linux.
Mint just the other week managed to not be able to find windows when setting up my usual dual-boot on a new board and drive. That was an annoying waste of time to sort out. I'm a techno guy and all but I really could have lived without having to manually screw around with grub in 2013. And I'm still not sure what happened, I think Win7 installed in UEFI mode, that I hadn't noticed existed really till then, and used GPT instead of MBR even though it was only a 1TB Raptor.
I found myself seriously considering ditching linux for awhile to go to a big SSD.
While I really do favor it, Mint with Mate anyway, it doesn't do anything Windows 7 can't for me, or anything any better really. And my computing life would be a lot more simple with one OS. It used to be that Linux was faster on a given box, but with 8 4ghz cores, 16gig of ram, a 10Krpm drive that is about to be an SSD, it's just not faster anymore. It feels different, and I like it, but it's not the draw it used to be.
Oh, and netflix not working blows. I run XP on a VM with virtualbox for work also luckily so I watch in that and it works well, but it's annoying.
It's really not Linux fault I guess, but programs and drivers and such I suppose. And I realize it's free, but being honest, so it Windows 7 for all intents and purposes for a lot of us.
I have keys on laptops I've bought and desktops, I even bought a boxed copy of NT4 once years ago. I'd pay for a Linux that fixed these things somehow. Maybe one day.