They gave up two minor league pitching prospects. I'm by no means a good source of minor league knowledge and have exactly zero knowledge of either prospect.
Soria will be a seriously welcome addition to the bullpen. In 33 1/3 innings he is currently rocking a 42:4 k/bb ratio. That will be a nice change of pace from can't-locate-my-fastball Nathan. That said, I believe Ausmus starts Soria out as the setup guy, bumping Joba to the 7th and keeping Nathan as the tentative closer on an extremely short leash.