I would advise against it. Doggie day cares are hit and miss, just like dog parks... only, when in doggie daycare you have no clue what's going on and for 'business' purposes the attendants are not going to let you know the 'bad' things that happen unless your dog comes out with a puncture or a bad scratch...
Yes, your puppy will be allowed to socialize, but more than likely, she will also learn bad behaviors. Depending on the type of dogs (personality, energy levels, etc) that also attend on the days your pup does, your puppy may end up learning that humans don't control situations and the only way to control a situation that is too rough or overwhelming is to resort to aggression.
In fact, most GSDs are kicked out of daycare after a certain age because they become 'too much' to handle... I do not believe this is because GSDs are 'too much to handle' I just think that after being pushed around so much they start to stick up for themselves and they are quite intimidating when they lay down the law.
Same thing happens with other breeds (such as boxers and pit bulls)
As for how I know... I use to work at a doggie day care... the things I saw were horrible. All I could think is... I would never let my dog attend without me (I was able to bring my dog on days I worked - but I would removed him and place him in a boarding kennel if there were dogs there that played too rough or bullied other dogs) ... play room attendants are only expected to do but so much, and the main thing is to prevent 'bad' fights... because dogs will 'tiff' constantly throughout the day and will have to be pulled apart. So long as no one gets injured nothing is every mentioned to the owners. I saw a lot of sweet puppies turn into reactive dogs because the puppies get bowled over and picked on a lot.
Murdock - GSD
Virgil, CGC - GSD
Tara, Reagan, Madison, and Jefferson - Aussies
The birds: Dante - CAG / Nero and Sunshine - Budgies