You'll have a hard time finding anyone who disagrees when you say Nisemonogatari is weak compared to Bakemonogatari. I'm puzzled that they decided to animate these books at all. Hopefully it won't scare away potential viewers from Kizumonogatari when the movie comes out, because that book blows everything else in the series out of the water.
Someone once described Nisemonogatari as "Koyomi's victory lap", and it really is just that. Taking the trophy tour after gathering his harem. Don't expect plot and you should be fine.
