As you explore Gotham City in Gotham Knights, you'll quickly see you can complete bonus objectives on most criminal activities and even story beats. Are these bonus objectives worth completing in Gotham Knights?
Is it worth completing bonus objectives in Gotham Knights?
It's entirely up to you if you want to complete bonus objectives in Gotham Knights, as it depends entirely on your play style and even on the character you have chosen to play. All bonus objectives are optional, but finishing them will earn you extra EXP (experience points) and crafting materials. Yet these aren't massive amounts. Think of bonus objectives as if you can do them great, but if you fail, so be it.
It may give you variety in your play style if you aim to complete them. If you're a charge-in assault type player, slow down and attempt to do some stealth to get some bonus EXP. The bonus objectives vary and seem to be completely random. You may get diffuse bomb missions to be stealthy and use stealth takedowns or get assault takedowns or grappling moves.
At the end of the day, it's ultimately optional whether you attempt to complete bonus objectives or not. It means nothing if you fail; if you succeed, hey, you get some free EXP!