I was extremely disappointed with the Beyond Burger-- it had a weird taste and I personally did not think it tasted anywhere remotely near real meat. It was oversalted, but I've heard some other people complain it's because the patty is already very salty and restaurants add more salt. It also might be a function of the fact that this was a vegetarian place and I don't think they're used to cooking burgers.
The Impossible Burger I was much more impressed with-- it still wouldn't fool me at all and I wouldn't quite replace beef with it yet, but I'm looking forward to seeing if they can improve it just slightly. For me, it doesn't have to taste exactly like beef before I would eat it over traditional burgers, it just needs to be a little closer. I would also like to try it somewhere that doesn't put as many fixings on it to taste the patty in a more pure form, since my burger was some miso-seaweed thing with strong flavors that could have been masking the patty (perhaps intentionally).