Creatine monohydrate causes water retention, and horrible gas. You can avoid this by using creatine hcl instead of monohydrate.
Personally, creatine has never negatively affected my mood, it's always done the opposite. The past week however I started using it again and my sleep has gotten a bit worse. It has the tendency to make me very energetic the first few weeks but that doesn't last so I'm going to stick with it for a bit and hope my sleep improves.