For most situations, your wrist should be slightly bent forward. It should feel like your wrist is in a resting state, rather than an extended state. As long as your wrist feels relaxed the majority of the time, and it doesn't hurt after you're done playing, you should be in good shape.
Should you bend your wrist when playing guitar?
Don't bend your wrist! Having a bend in your fretting hand wrist puts strain on the tendons in your wrist, which can cause tendinitis when you practice a lot. You want to make sure you're not putting any unnecessary strain on the muscles and tendons in your forearm.
Is playing guitar bad for your wrist?
The guitar is an addictive instrument, and guitar players do get obsessed with perfecting the way that they play their songs. Excessive practice can result in wrist pain, joint pain, forearm pain, elbow pain, and posture problems, along with many other issues.