First off, any existing beta characters will not be wiped upon the commencement of open beta. That means anyone already playing, whether in the closed beta or as part of the game's recent stress test, will get to keep their character that they've worked on. Second, while in open beta the game's price will be dropped by five euros (about $7), which means that if you like the game, it's even easier to decide to make it a full-time home.
Downsides? Only one - as community manager Maerlyn points out, the testing will be based on a single server cluster in Stockholm, so their may be server caps or slight connection issues depending on distance. But that's hardly enough to take away from the good news. If you've been waiting for Mortal Online, your day is almost here.
[ Thanks to Bartillo and David for the tip! ]