iTunes / App Store reviews are a mess and a disgrace for Apple. I submitted my 5-star review of Marvin many days ago, but it still isn't showing up. As a rule, I don't even make the effort to submit App Store reviews, because it's just not worth the trouble. I made an exception for Marvin, but as you can see, it hasn't helped any.
iTunes / App Store reviews employ the incredibly stupid principle of geographical isolation.
And so I, residing in a small Central-European country of 5 million, can never see user reviews from any other country except my own tiny country. Naturally, there are only very few reviews, then, compared to (say) the US, French, or German App Store, and the star ratings are completely unreliable. Even if my 5-star Marvin review eventually shows up in my tiny country's App Store, you guys in all the other countries of the world will never get to see the review anyway.
This whole reviews arrangement by Apple is so stupid it's mind-boggling. Please don't make me talk about it any further, or I'll just explode.