That's an interesting case. I might make some wild guesses based on what I see:
1. vk ports features from fb 3 to 6 months after they appear (share-widget, like-widget, connect-widget, possible friends)
2. vk's got a comprehensive search engine with lots of filters by age, city, gender, current status (married, single, in active search etc.). Lots of people I know use vk for dating. I might be missing something, but I didn't find such a thing for facebook.
3. vk's got native music and video upload. By native I mean that you don't use any third party application/service to do this. Everything's hosted on vk's servers. That's the reason copyright owners sued vk several times (RIAA even blacklisted the guys). However, they [copyright holders] lost in all the court cases.
4. VK offers cheap contextual ads. While not exactly a killer feature, it is very nifty for business, -- they only charge per-click and if you get the targeting and ad text right, you'll get more visitors than you need.
5. Another random guess is that it's easier for a German than for a Russian to migrate to English service.
The most important factor is that number 3: music and video uploads. You just didn't present it as it is. Facebook also has an option to upload video. But the real difference is that VK became practically the alternative for torrents: all the movies and all the music is there. On their servers. Free to search, watch and enjoy. Facebook doesn't have and will never have it.
So if you have all your friend on VK AND you have all the entertainment stuff there - why switch?
Unless Facebook comes with some interesting strategies to pull the users, the status quo will remain as is. And from what I hear and see, FB is putting a significant effort into this. It'll be interesting to watch in the nearest 1-2 years.
5. Another random guess is that it's easier for a German than for a Russian to migrate to English service.
In principle, Facebook is localised. I could imagine that few apps are translated to German though, and even fewer to Russian, except those built by native developers; (I don't use any apps, so I don't know) that native developer pool ought to be the same as the one building VK (or VZ) apps. Assuming Facebook does a decent job of filtering localised apps, I can't imagine this to be a massive issue for users.
I can only assume the media upload is what keeps people coming back.
All of the other reasons you mention seem to be reasons why businesses would prefer VK over Facebook, but surely it's the users that are the key?
See, that’s what I would have thought about StudiVZ and yet Facebook could spread in Germany like a wildfire. StudiVZ still has millions of users but Facebook has those same users, too. (This is only anecdotal evidence but Facebook also seems like the busier place to me, activity has transitioned from StudiVZ to Facebook.)
This tells me that even if a social network seems to have a particular market cornered, a competitor still has a chance. (Which, I think, is quite nice to know.) Network effects are obviously important and have to be considered by anyone who wants to build a social network but I think there are certain properties of social networks that dampen network effects: Signing up is easy and free, for one, and rebuilding the social graph, while some work, is far from tedious. You only have to add some friends and recommendations get you the rest of the way.
I wonder if Seznam really is more popular than Google in ČR. Do you have any data to support this? Also I wonder what the deal is with Jyxo.cz. How much behind Seznam is it nowadays? Wasn't it technically superior?
1. vk ports features from fb 3 to 6 months after they appear (share-widget, like-widget, connect-widget, possible friends)
2. vk's got a comprehensive search engine with lots of filters by age, city, gender, current status (married, single, in active search etc.). Lots of people I know use vk for dating. I might be missing something, but I didn't find such a thing for facebook.
3. vk's got native music and video upload. By native I mean that you don't use any third party application/service to do this. Everything's hosted on vk's servers. That's the reason copyright owners sued vk several times (RIAA even blacklisted the guys). However, they [copyright holders] lost in all the court cases.
4. VK offers cheap contextual ads. While not exactly a killer feature, it is very nifty for business, -- they only charge per-click and if you get the targeting and ad text right, you'll get more visitors than you need.
5. Another random guess is that it's easier for a German than for a Russian to migrate to English service.