Ooof. Where to start...
Well, first of all, two things can be true at the same time. Lee's talents have been discussed plenty by people who worked closely with him, as well as by outside observers who have commented on Lee's charisma and salesmanship as being integral to the Marvel's success. However, on the first part, when three of the foremost critics of Lee who accused him of stealing credit are Jack Kirby, Steve Ditko and Wally Wood, it's pretty hard to accuse them of not understanding how the comics business worked and where the lines between creator and marketer started and stopped.
Second, no one denies Lee the magnitude of his influence largely because he's virtually always the first one credited throughout most tellings of the Marvel Comics story in the creation of the characters. Not Jack Kirby, who had already been well established in the industry and would take basic outlines, and sometimes one sentence blubs from Lee (sometimes the only writing that Lee contributed to many issues of the comics), and provided the rest of the plot, the dialogue, and the artwork. Similar accounts came from Ditko and Wood who both left Marvel and were vocal with their criticism in the years afterward.
So, in my opinion, no. Not poor Stan. Poor Stan for the people who took advantage of him when he was much older and people were squabbling over his estate and likeness, but not poor Stan for fair criticism of his time running Marvel. He got plenty of accolades throughout his life, and the criticism was quite fair.