The only historical reference to John the Baptist outside the Christian Gospels is in a history by Josephus, a Jewish historian. The short paragraph presents a favorable view of John as a holy man who encouraged people to live pure lives. Some say this passage might not be from Josephus, but added in by later Christian influence. (See both http://www.jewishencyclopedia.com/articles/8733-jo... and http://en.wikipedia.org/wiki/John_the_baptist). Though Josephus says John the Baptist was an Essene, modern scholars are less certain of this.
After that, we can find no opinion of John the Baptist in medieval or modern or recent Jewish thought. (My wife is a professor of Judaism and very aware of Jewish thinking on the Christian New Testament, and together we have not come across anything.)