+1
I won't miss expose or spaces from my MightyMouse.
Lucky you... for me getting Spaces with a click is something very important as I use it a LOT.
I don't use Exposé that much, therefore I stick to keyboard or corners for it, but Spaces is very important to me.
Hot corners are the way to go anyway, IMO, so you can contiguously drag an object from one window to another through spaces/expose.
It would be interesting tracking the overall distance you do every day just to reach a corner (and of course the time it takes to do that).
For some people, the numbers would be amazing...
I do, however, use the middle button (on the scroll ball) for Dashboard - but, it's no big deal. Having the momentum scrolling (and no physical ball) will be well worth it.
So in the end, you use the button in the middle... but you're willing to adapt your behaviour to Apple's lack of usability (and if this feature of a middle button is not provided, it's a big big usability mistake and Apple knows it).
If you fall for the multi-touch thingy... glad you like it. I do like it too, but I'm not exchanging a multi-touch for a middle button and its scroll ball which does the same thing.
Even though Mighty Mouse is said to be crappy for its usability and ergonomics, I think that it is quite useful, but this new Magic Mouse... is a step back if they don't provide some features that they should provide with the top-selling marketing idea of multi-touch...
I hope... I do really hope... 10.6.2 includes at least the middle button, and it would also be interesting to include the zoom as I can do that gesture on the surface of my Mighty Mouse without much trouble (and its surface is not as flat as Magic Mouse's).
In a few days we'll see if the 69 dollars (or euros... this is funny... when euro is stronger than dollar... the exchange rate for Apple is 1:1, but when it was the opposite... it was different...) are worth it or not