Well I wasn’t fooled by fake Luke not even for a second, but didn’t know how he was doing what he was doing until revealed. Not only the footprints, but the haircut, hair color and lightsaber totally gave it away for me. That took tension away, which made it all a bit disappointing.
What tension? That he wouldn’t die? Wouldn’t the tension of that be cut anyway when the walkers don’t leave a scratch?
Not to mention, of course, that he does die.