Bayern is a big favourite with odds of x1.33, while betting on Leipzig, you can pocket x7.50. I think bookies underestimate Leipzig team a bit. Leipzig are horribly inconsistent this season, especially when we consider all competitions (i.e. including the Champions League) but they still have one of the best defence in Bundesliga (second only to Bayern) and they noted a good performance last weekend when they earned 3 points on Eintracht (something that Bayern failed to do, as they drew with Frankfurt 3-3 back in October).
I actually do not think it is them underestimating the Leipzig team. Because they have been so inconsistent in this season it is highly unlikely that they are going to win the match against the team that is on the top of the table. They have lost the previous match against Mainz. But I do not think they are going to lose this one. I think they are at least going to get a draw and one point from this match. I know that the people have underestimated Leipzig but I don't think Bayern Munich is going to make that same mistake.