One film that's really underrated and consistently gets trashed is MOONRAKER. While far from being a perfect film, it does get a lot of things right and is always consistently entertaining.
Roger Moore's at his absolute best in MOONRAKER. This *is* the superhero Bond, and done as the superhero Bond should be. He's beautifully charming and sweet in his scenes with Corrine (perhaps my favorite seduction moment in the series), and also shows some real acting talent (watch as he exits the centrifuge... classic). He delivers his lines with panache and style and is always confident and cool.
This film also gives us some of the best set-pieces to be had in a Bond film. The opening sequence where Bond tumbles through the air without a chute is fantastic stuff. Bond facing death in a centrifuge is the stuff of classic Bond adventures. Bond fighting a thug in a glass museum? Outstanding. A boat chase down the river with a gadget-laden boat? Great.
Furthermore, Michael Lonsdale's Hugo Drax is one of the most delightfully fun villains of the series. He's intelligent and menacing and has an incredibly sharp wit. Brilliant. There's some real brutality here too, like when he sends his dogs after Corrine (one of the darker moments in the series).
Then there's the matter of just absolutely audacious scale, something I've always loved in a Bond movie. I've never, ever found anything wrong with Bond being really over-the-top. This movie does cross the line as soon as things head to outer space (the space battle just doesn't work on really any conceivable level - perhaps if Bond and Holly had just figured out how to sabotage it on their own, it might have worked), but before then, it works. It is "Bond and Beyond" and there's something to be appreciated about that.
If MOONRAKER has a serious flaw, it really has some quite campy stuff in it. The Jaws stuff is completely ridiculous (though not *that* far removed from what was done with the character in THE SPY WHO LOVED ME), and there's cheap gags here and there. But it's all meant in good fun, so it's hard to hate them too much, because you are supposed to be laughing at them anyhow.
And in spite of what MOONRAKER does wrong, it remains consistently entertaining. It's a blast to sit through, even if you're somewhat shaking your head at it all the time. It's tongue-in-cheek entertainment, and there's nothing wrong with that.