Warning: I am only a lukewarm fan of Peanuts.
The script was taken directly from the tv special. I don't think they deviated at all. The actors were OK, but not the best. I got the feeling that they were passed over for other more acclaimed shows.
May main issue with the show was the length. The first part was 45 minutes long. This was fine and I expected this. I paid close to $300 for four tickets and assumed the show would last 1.5 hours. What I didn't expect was for intermission to last close to 25 minutes, though there could have been a problem going on backstage. What made it worse for me was only the first 10 minutes after the intermission was there actual acting going on. After 10 minutes, the show as over, exactly where the tv show ended. For the next 30 minutes, the cast sang Christmas carols. What the? I did not pay that much money to listen to actors sing Christmas carols.
Now, many in the audience loved it and sang along. However, I feel that I can listen to these in the car if I want to listen to them (and often do).