1. Compare app description in Ovi Store with Apple's App Store.
Ovi forces to create square screen shots what makes apps look ugly, because they are designed for screens with 4:3 or 5:3 ratio (or some other). It's never a square (1:1 ratio), so app screen shots look awful. Not to mention that in Apple's App Store screens are full sized, while Ovi forces to create very tiny screen shots where user can't see anything.
App description in Ovi Store is very short compared to Apple's App Store.
2. Ovi Store doesn't allow localized screens. For any localized version user would see English screen shots (most probably you'd use English language for screens) . And that's confusing. Simply by looking at screen shots user doesn't know if app is fully localized or not (because often only description in Ovi Store is translated but not an app itself).
3. There is no link to publisher web-site from Ovi store app page. So there is no way for user to get any additional info about the app that he is interested in. App Store, on the other hand, allows link to the app's web site.
There is no rational explanations for limitations like these.
Are you ready to buy an app that looks ugly on screen shots, that has a very short description, when there is no link to support (app) web site and when there is no info about level of app localization for your language? Yeah, right.