Wedbush Securities' Michael Pachter suggested that the entrepreneur's casual dress sense could hinder opportunities with potential investors.
"Mark and his signature hoodie; I mean, he's actually showing investors he doesn't care that much; he's going to be him, and he's going to do what he's always done," he told Bloomberg.
"I think that's a mark of immaturity. I think that he has to realise he's bringing investors in as a new constituency right now, and I think he's got to show them the respect that they deserve because he's asking them for their money."
However, Pachter went on to praise Zuckerberg's management skills, likening the young billionaire to late Apple co-founder Steve Jobs.
He added: "[Zuckerberg] is well-suited to be the chief product officer, the chief user-experience officer, to manage the design of the user interface, to decide every feature that goes in."
Facebook recently rated its shares between $28 (£17.30) and $35 (£21.60), which values the company at between a massive $85bn and $95bn (£52bn-£59bn) ahead of its forthcoming initial public offering (IPO).