Perhaps Planet Hollywood’s stock should be called Buy Hard With a Vengeance. The glitzy eatery went public April 19 with an initial public offering priced at $18 a share and burned up the NASDAQ exchange by reaching $31 during its premiere. But it’s not clear if the stock has legs: Prices dipped the next trading day to $26 but edged up to just over $27 at press time. Going public has paid off for the chain’s celeb co-owners — including Sylvester Stallone, Arnold Schwarzenegger, Bruce Willis, and Demi Moore — whose shares are now reportedly worth $550 million. But is it a good buy for the average investor? New York financial analyst Darren Frankel advises starstruck clients against it. ”It’s a totally unimpressive stock because the restaurants aren’t especially profitable,” he says. ”Entertainment stocks are generally crap.” Planet Hollywood wouldn’t comment.