I've had the Skull Shaver for several months. I've used it "dry," "wet," and with shaving cream. It has done a credible job.
Using it dry should only be done if you haven't shaved for a day or two at most. In that instance, you really can get a decent close shave in a couple minutes or less.
Wetting the scalp first seems to result in a closer shave, but not enough that people other than yourself will notice.
Using shaving cream is the best option, and is absolutely necessary if you haven't shaved for 3 or 4 days. Even though irritation is minimal even when using dry (for me, anyway), there is no irritation when using shaving cream. You get a good, close shave.
However, and I think this is important, if you believe your scalp and face will be as smooth using SkullShaver as when using a regular multi-blade razor, you will be disappointed. You WILL feel some stubble on face and scalp even after your best effort. But just about no one else will notice it.
John Benante gave Skull Shaver a 4 star review