Nobody wandering blindly into a movie theater showing Avengers: Age of Ultron — certainly no one who hasn’t seen the previous installment, anyway — will wander out 142 minutes later looking any more enlightened. Whether you see in 3D or 2D, in IMAX or a small screen, Avengers: Age of Ultron is a massive, gleaming, machine-tooled, paper-thin movie. Pretty much from the fade-in, we’re hurled straight into the middle of the Avengers’ battle royal to penetrate the Fort Knox-like stronghold of Baron Strucker (Thomas Kretschmann). In that castle, Loki’s powerful, misused scepter lies hidden and soon enough, thanks to narcissistic Tony Stark (Robert Downey Jr.) who wants to build a robot to keep the world safe, the way gets paved for the ascendance of Ultron, the Terminator-ish, sentient A.I., voiced and CGI-hosted by James Spader with enjoyably honey-voiced, snooty condescension. In no time flat, the newly minted AI is out to not only smash the Avengers but also to smash all mankind to smithereens.

Director-screenwriter Joss Whedon has many boxes to tick and many superheroes to service, including the addition of Vision (Paul Bettany) and the Tony Stark-hating twinsies Quicksilver and Scarlet Witch (Aaron Taylor-Johnson and Elizabeth Olsen), the latter two of whom are nicely described: “He’s fast. She’s weird.” Each of three newcomers makes a vivid and lasting impression. With so much going on, it’s no wonder that the overstuffed, angst-ridden film involves lots of frantic cross-cutting, story-juggling, philosophizing, and at least five huge action sequences that don’t so much entertain as try to batter us into submission.

On the upside, the intra-team bantering we’ve come to love is snappy (if over-plentiful) and Johansson, Ruffalo, and Spader are especially good. It’s also gratifying to see the previously underused Hawkeye (Jeremy Renner) getting more screen time and even beginning to emerge as a much more interesting character. Overall, though, for all of its cheesy fun mixed with doom-and-gloom observations on the plight of humanity, this Avengers leaves us with the nagging feeling that we’ve been here too many times before. It’s tough trying to recuperate from cape-and-spandex fatigue when the march of Marvel and D.C. is so relentless and omnipresent not only in movie theaters but also on TV. **½