I think that, given another year, they might be able to get decent traction. Their biggest problem of course is going to be marketing and, historically, that's always been Microsoft's biggest problem.
Two of my friends have bought WP7 devices after toying with mine. That's fairly remarkable because I live in a country where it's not advertised and the UI isn't even translated to the native language yet.
Plus you get the most recent OS version pretty fast compared to Android
http://c27718.r18.cf2.rackcdn.com/wp-content/uploads/2011/10...
The phone suffers from poor marketing and "Oh gross, MICROSOFT makes it" response. The average person automatically buys an iPhone or Android because they think those are the only options. Techy people automatically assume Microsoft is awful at everything.
I've recently moved to Chile and was given an Andriod (froyo) by the local carrier, and I've committed myself to using the Android for 2 weeks. I really miss my WP7.
I've used iOS (iPod Touch), WP7, WebOS and now Android, and WP7 is beautiful and snappy. It is very well thought out and the integration of content into the device is amazing. I am yet to find anything on Android which I think is done better than on WP7. iOS is probably more refined, but not as well integrated, and not as beautiful (but that is a judgement).
I'm still surprised every time I seem somebody else with a WP. What also surprises me is how many people play with mine, and then suggest that they would consider it when replacing their phones. The common line seems to be that 'everybody has an iPhone, I want to get something different'.
Also, I can't find a link now, but I believe HTC said 1/3 of their shipments last quarter were WP. That's huge! It doesn't mean that they are selling well, but somebody somewhere is ordering them. Maybe it is just MS giving them to their employees.
The Lumia 800 is also a brilliant phone that I can see gaining some decent traction in the next couple of months.
Regarding the voice commands, I've only ever used them to try them out (and results were patchy, maybe my South African accent), I couldn't imagine ever using them in everyday use, so I'm not too fussed about Siri (although it looks amazing from a tech point of view).