You can watch it online at this link, or watch it here:
Senses of Cinema says,
Filmed seven years after the war when memories of the conflict were still fresh in the minds of its contemporary audiences, The Big Parade is definitely not a pro-war film but neither is it as anti-war as its director once thought.
The New York Times has a review of the DVD release that says,
the film remains a heartfelt but shrewdly judged blend of comedy, romance, action and tragedy — a movie that perfectly embodies the classical Hollywood ideal of providing something to appeal to every member of what, in the 1920s, was a wide public still unsevered by demographic categories.
It's included in the book 1,001 Movies You Must See Before You Die. Rotten Tomatoes has a critics score of 100%. FilmSite has background and an extensive and detailed plot description. Slant Magazine says, "For all its grandeur, The Big Parade concerns the individual response to forces bigger than any one person".