Patlak, not sure where you are coming from (in the sense, Symbian fan, N900 fan or so) but if
M5 <=> Maemo Fremantle
i totally agree with you.

regarding the "unpopularity" of wp...
i don't think it is only / mostly

• customization & setup freedom
• availability of (free) apps
• number of home screens
• (anything else i forgot ?!?)

rather then

• the unpopularity of m$ (i know, i know, it's the most used PC OS bla bla, but, honestly, do ppl have a choice? whenever you buy a (new) PC / laptop, you have to buy a m$ license, might as well use it, even if one ends up shrinking the partition & installing a GNU/Linux next to it (& possibly using it more)
• m$es catastrophic reputation / image on the mobile phone market (wm anyone?)
• their trollish patent war behaviour (?)
• m$ = $$$$$; yes, they make a $h!t load of money, but a lot of that money comes from consumers pockets, too; like i said, the OS licences are usually "included in the price" & hey, they even offer a browser and anti-virus with it but anything else... $$$$$

Apple isn't much different, but they had "new gadget" effect going for 'em, and a AAA reputation.
and Android? well, the devices have to be paid for too, obviously, but they had the "cheaper" alternative compared to Apple going for them and five years ago, Google's reputation maybe wasn't (quite) so bad (yet)