Open Ecosystem (Android, Maemo etc) or Closed Ecosystem (iOS, WP7 etc)

In the past two years, I made a gradual shift to open source ecosystems, be it on a PC or on a phone. First it was Android and then I moved to Maemo (which is arguably the most open mobile operating system) and on my PC, I moved from a windows environment to Ubuntu. Last weekend, I was given a HTC HD7 (running Windows Phone 7 OS) to test. You can read the first thoughts here and the review here, penned by Giridhar. In the next few days, I am going to focus on whether the closed ecosystem and the UI of wp7 can please someone like me who is addicted to open source and open ecosystem. In the recent past, I have been very open in criticizing the closed nature of WP7. Will this trial of HD7 make me take back those words and say that closed nature is indeed better?
In the mean time, please do share your thoughts. Which approach do you think is better? An OS that is yours to tweak/tune/customize or an OS that is closed to let you do any tweaking but excel in what it does out of the box? An ecosystem that has no boundaries/restrictions or an ecosystem that is closely guarded and controlled. What should an end user try? Android/Maemo that makes the user understand OS in a better manner or WP7/iOS that makes the user use the device the way it is without the need to customize and fine tune the OS?