Joe Ossanna took extensive and careful notes on the visit, and I wrote them up in machine readable form; I still have the whole original file. The file-system date is 11 Feb 1978, but it must have been copied or edited a bit after its creation; it was clearly written before the introduction of the VAX line in October 1977, but also after work began on the Interdata 8/32 project in early 1977.
An edited version of our VAX thoughts is available here. The sections in [ ] are notations mostly added in 1988.
About June 1988, I posted to netnews my 1977 version of Ossanna's notes, in approximately the same form as linked above. I also saved the netnews posting; it's a 10+years-after critique of our impressions from then.
The main observation I'd make today is that over the years, Digital did much better in understanding software than looked likely in 1977 or perhaps even in 1988. Considering Alpha, I'd say hardware too.