I think that's correct -- he seems like a Hubert Humphrey slightly updated for our time. That's not a knock. Humphrey was a very big deal in his day, he lost to Nixon because he just couldn't escape LBJ's shadow on Vietnam and young Dems never forgave him for that and wouldn't vote for him. Walz isn't much known to us, at least in particulars, but I don't doubt he is known and respected in WI and MI.
Our junior Senator Fetterman lobbied strongly against Shapiro, as did most of the progressive caucus and, I suspect, Bernie. Walz has more experience than Shapiro and this is a far less dangerous move for him than it is for Shapiro, whose political future could be dimmed if Harris-Shapiro were to go down to defeat. There is serious discord between Fetterman and Shapiro, who feuded over Pardon Board votes and are political rivals. Bernie took a long while to come out in support of Harris.
In other today election news, The Silver Bulletin, of Nate Silver 538 and baseball analytics fame, is first to give an edge to Harris in the election (51% odds of winning electoral college). Silver isn't a pollster, he is an aggregator and analyzer of published polls, who does a weighted (on poll history of reliability and methodology -- sample size, registe red vs likely voters, with or without third party candidates). Not a big indicator, but in line, if a bit ahead of, numerous polls showing the race is approaching toss-up territory.