Released on November 18, 2012, Miiverse is Wii U’s take on social networks, taking ideas from Facebook and Twitter. Miiverse originally harbored a limit of 100 characters per post. Now, Miiverse has a limit of 200 characters per post. I doubt there is any reasoning behind these limit. Now that the Miiverse limist of 200 characters per post is greater than the Twitter limit of 140 characters per post, Twitter users will be right at home.
I have not yet integrated Miiverse into my gaming life. I prefer face-to-face social interactions that games like New Super Mario Bros. U encourage; I’d much rather trash talk Bowser to my friends next to me than do the same on Miiverse.
Source: Nintendo Life