If you keep in mind what Kreator, Slayer, Dark Angel and Morbid Saint were up to in 1986, Gargoyle is halfway there style-wise but suffers from a lack of production and a vocalist. Yes, a vocalist can be a deadly disease. Fortunately the symptoms only sporadically show. The symptom being high pitched screams.
High-pitched screams were common utensils in '86 speed and thrash but obviously they have to be convincing. This is where Dave Necro falls short. His vocals are aggressive, balancing between old Kreator and Morbid Saint. But when he decides to thrown in a scream (which he does several times on each song) he just sounds like a parody. Had he not done that, this demo would've been so much better and convincing. If I try to imagine this demo having the production of Spectrum Of Death or Pleasure To Kill and Dave Necro joining Screamers Anonymous, it would probably have a huge cult status by now. In this form however it sounds too much like your average low-fi kitchen recording.
The most annoying thing is hearing a band with potential, aggression, catchiness and knowing they never got signed nor released a full length album. Such a shame the world hasn't gotten more of their easily digestible furious old school thrash with a decent production. Of course in terms of quality it wouldn't have come close to the classic furious thrash metal albums from '86 but it sure as hell would've been another welcome release from that era.