The game is very odd, frankly, difficulty-wise.
Exploration-wise, the game is much more challenging than Banjo-Kazooie and while none of the Pagies ever reach the complexity of Tooie's toughest Jiggies, the general level of challenge in finding everything is very high. There are some fiendishly hidden collectibles that few players will find without consulting a guide.
However, combat is very schizophrenic ; encounters are either incredibly trivial or brutally difficult with no middle ground. Basic Corplets are pushovers, most Bees can be cheesed, and Corplet Punishers are a total letdown. Likewise, some of the bosses are surprisingly simplistic and just don't compare to how tough Tooie's bosses were. On the other hand, large mobs of Corplets supported by Bees will absolutely tear you apart even with the last moves unlocked and a fully-powered duo and boss-wise, the first and final bosses are disproportionally difficult. This wouldn't be so jarring if all bosses were brutal (in fact, I would like that) but the fact that the first boss is so hard compared to most other bosses is jarring and unfitting.
Overall, the game is harder to complete than Kazooie but it doesn't tax you the whole way like Tooie does (and as much as I like Yooka-Laylee's final boss, it just doesn't compare to the monstrosity that was the Hag-1).