Im sure they will find it fun to play in....
That being said...they wont be used to colder temps though, so just ensure they have hay in front of them which will keep them warmer, and if need be, throwing light blanket on them may help.
My horses are out in -40c and are fine, but they are accustomed to that, not all horses would fair well in cold temps if not used to it.
But yes, a little snow didn't hurt anyone...a.bout time you people get to share it w us :)
Horses are like chips...you can never just have one