Showing ios app store comments from different country
Not sure if there is a "main" webpage to browse from directly, but if you do search for the name of an app and then "itunes.apple.com" or "Mac App Store" you will get to visit the app's page in your browser.

Take Reeder for example:


Mac
iPhone/iPod
iPad


You can change the country by using the country flag on the bottom right of the page, or directly on the URL if you know the country code.