As webcomics go, this one is pretty good.
It may not be an artistic masterpiece like Lackadaisy or minus, but I'm glad I took the time to read Zap! and will stay with the series until it's finished. The story is pretty familiar: an idiot hero with amnesia and psychic powers is on the run from an evil galactic empire and falls in with some rebels, including a love interest. But then, some new wrinkles get added as we learn that our hero is more than he seems and his "friend" from before he lost his memories shows up. The writing is really what makes Zap! work. The characters are fun and likable (or villainous and diabolical), the humor works and the hints and plot setup are intriguing. The art starts off pretty unimpressive, but gets A LOT better as the series progresses. Some of the later fight scenes in particular help this one rise above the pack. If you check it out, at least try to read through the Hi Ho Casino! chapter, as that's the high point of the series so far.