I use Vopium to reduce my phone bill when making international calls and calling back home from other countries. Very nice product, huge savings, no subscription fee, works seamlessly when making calls, and easy to install from their homepage. However, the obvious is to install such tools from the app store, right? So when I had to reinstall it this week and went for the Nokia App store, it was empty. There was just one tool in there: A new version of the Nokia app store (named Ovi Store). Using an expensive data connection in a foreign country, that's just extra costs.
Nokia's usability department seems to have had a vacation for the last couple of years, and this new version isn't better, even though it should be a high priority for Nokia to keep their smartphone market share. The online version of Ovi Store isn't much better, because when I go into the online store using my phone, it first tells me that there is a better way, than the HTML version: I can use the Nokia Ovi Store app. It asks me, if I want to use the app or continue to use the website. If I choose to use the website, it shows the first page of the mobile version of the website, and then it automatically starts the Nokia Ovi Store app, moving away from the HTML version. If I'm not allowed to use the HTML version, why did it ask?
If Nokia's market share for smartphones continues to drop, usability must be the reason. Fortunately, Vopium's homepage works perfectly in the Nokia mobile browser and solved my problem, I didn't have to use the Ovi Store.
If you are worrying about usability in your project, I can recommend the usability works of Søren Lauesen. In contrast to Jakob Nielsen, Søren's works contain more generic and deterministic methods.