First, Y! Mash is cute. Yes, cute.
Its more related to Myspace than Facebook, so it's definitely not the leading contender to channel a river of relevance or act as the premier online hub for your personal brand - at least not in a Facbook capacity anyway. But that doesn't mean that we should write it off either.
This is the new world of Social Media, and Yahoo's Mash represents the latest network where people will experiment with existing and new relationships - many of whom, are already among your many networks.
Like Facebook, it shares a compartmentalized design template featuring modules that can be moved around to create the profile design you prefer, including the ability to upload backgrounds, CSS stylesheets and also to simply customize the colors.
Its absolutely effortless to customize your profile and there are already several applets to further personalize the page, and, even add some fun little games for viewers - without touching HTML.Mash does offer some very interesting features that make it fun, friendly, and surprisingly versatile.
For starters, you can edit not only your profile, but your friends pages as well, which I think is very clever.
It also features the ability to bring in modules, which are basically Facebook-style widgets that add embeddable functionality to each page. For example, you can add RSS feeds, Twitter status, flickr photos, Last.fm artists, and Youtube videos - among many other games, time wasters, and tools.
Mash also features a pulse stream. which is similar to the newsfeed of Facebook, that highlights the latest updates and activity from you and your friends.
Surprisingly however, the social network is missing the viral functionality of searching for friends. While you can integrate various address books to find and invite friends, the ability to discover them organically is missing. In fact, the search box on each profile is simply for Yahoo search.