I watched it today, and enjoyed it. I liked both of the first two, and I liked how the second movie got a little crazier than the first, but in the same spirit. And here, they went another degree with it. This is not exactly Oscar material, and it was never meant to be. Just crazy, silly fun. I don't know if it was as good as the first two, but it was comparable.
The reconciliation with Death was surprisingly touching. Bill and Ted's "reunions" with their older selves over the years was strangely touching as well, even as I was laughing out loud. Bill came up with some deep stuff about how we regard our future and past selves, and his observation on how Ted had more trouble getting along with his older selves than he (Bill) did was interesting.
It seemed like the "theme" that Bill and Ted literally could not think of themselves in the singular, but always as the two of them, should have either been developed a bit more, or had more payoff, or something. The couples therapy angle felt like one subplot too many to cram into the relatively short runtime, but it was too important to drop. On the other hand, they were together in every scene, as were the girls. But it seemed like there was supposed to be more of a message there.