I don't have a great recollection of the 2nd and 3rd films, but I still feel comfortable saying that this is the weakest of the bunch. Based on reporting, the budget for this entry was significantly reduced compared to the previous films ($85M vs $135/$150/$145), and you can tell. The animation is noticeably less detailed and the absence of the furious 5 was almost certainly a cost cutting measure. However, the lower budget isn't what drags the film down. In fact, I think it makes sense to push back against bloated animation budgets. Do we really think the primarily younger audiences are going to care about the graphical fidelity of the animal fur or how realistic the water simulations are? I think studios are realizing that there are diminishing (perhaps even zero) returns at higher budgets. While I couldn't find any reported numbers, I expect that animation budget for Adam Sandler's recent Netflix film, Leo, was comparatively low, as they leveraged a stylized/simplistic style that still allowed for all sorts of visual creativity. The point being, creative and engaging visuals don't need to be expensive and ultimately it's the story/characters that do the heavy lifting. Unfortunately, that's where this film disappoints. The story is incredibly rushed, at some points feeling like they cut entire sequences (e.g., [spoiler]when Zhen gives Po a cryptic quote about footprints, we cut to him following foot prints through the snow, and then we cut back to Zhen following up on the cryptic quote[/spoiler]. The movie feels like it's going through the motions, relying heavily on call back material in lieu of anything more original.