It varies for me. Occasionally I'll be as clear headed as in waking life, but more often than not I'll be slightly altered in some way. Usually my judgment is somewhat impaired and I have poor impulse control. But I think the most striking difference is that I seem to be completely "in the moment" and give little thought to what I'm going to do or what I've just done. Not an altogether unpleasant experience, but it can make it difficult to complete some of the lucid tasks I've set for myself.