The missing # key is annoying, although it's not the kind of thing that would make me change operating systems. Apple's chosen shortcut for the '#' character is Alt+3 which is frustrating for terminal users who use Alt as the meta key—for example, it makes it hard to enter channel names in Irssi.
That's what I do on my MacBook Pro. It was much more palatable than discarding years of typing experience.
I don't dispute that it works. But it does rather detract from, well, the aesthetic elegance of the machine. Apple has these fancy backlit keyboards--it's a great shame to make the keycaps wrong.
Plus, it also causes big problems when I let others use my machine. Hunt-and-peckers don't stand a chance when your keys are mismatched. Though they probably struggle even with the regular Apple layout--good luck finding # on the keyboard, since Apple doesn't deign to print it. Sure, once you know it's option-3 it's not so bad, but I don't know how you're meant to just figure that out for yourself.
And the thing is, it's all just gratuitous. Apple's layout isn't in any meaningful sense better. It's just... different.
UK keyboards on PCs have a dedicated key for #/~, " is shift-2 and @ is shift-'. £ (currency symbol) is shift-3.
On a Mac the " and @ are the wrong way round (shift-' and shift-2 respectively), and the key that should produce # instead generates \. The only way to get a # is option-3, which is not marked on the keys. The Mac "UK" layout is basically the US layout with £/# reversed.
