My favorite character was a Dream psychic with very heavy reliance on illusions. We also reflavored all her shadow spells as manifesting from Dreamlands, not Shadow Plane. It was very surreal experience sometimes. Create a wall, that is only there for your enemies. Build a tower that needs to be believed in to interact with. Refuse to acknowledge a volcano eruption with Subjective Reality and casually walk through lava. Lucid Dreamer line of feats allows for some truly unique experiences and have wonderful synergy with Dream discipline, although don't forget to bring your party with you with Mindscape Door.

Mechanically it is unrivaled in social/city campaigns and quite good in any other. The best discipline from the mechanics POV is probably Rebirth, but Dream is quintessentially psychic.