I think he was marginally successful in the US, but really seemed to have success in the UK.

I remember watching Hall back in the early 1980s on a little show called "Fridays". The whole show was a sort of precursor to the jaded sociopolitical bent comedy was about to take in the mid 1980s with comedians like George Carlin & Bill Hicks leading the charge.

"Marginally successful" includes writing for and starring on SNL, having a Showtime special or two, having a successful standup career, writing for Letterman, etc.?

That's "marginal?"

SteamPoweredKleenex, that's quite an unexpected defense of Hall's accomplishments. Something personal at stake?

Clearly Hall's accomplishments in the US are noteworthy, but they are not in the same category as say Carlin, Louis CK, Gervais, Fey, Adam Sandler, and likes. Maybe more like Denis Miller, who I would say has been marginally successful. Hall has done much better for himself in the UK. His wife is British, so perhaps this is just a matter of spending more time there and working there, I don't know. What does seem pretty clear is that compared to successful US comedians, like those I listed above, Hall's success in the US is marginal. I would also say marginal compared to his UK success.