Remember Eight Legged Freaks? The sort of entertaining, sort of horrible movie about giant spiders attacking David Arquette? Spiders 3D looks the total opposite of that. Wait...what I mean to say is take Freaks, subtract the fun, add more bad CG, and you get Spiders 3D.
This is the paragraph where I'd do a plot summary, but I can't seem to muster it. This film is about spiders...and 3D. It's in the same vein of films as Sharktopus, the "haha bad monster movie haha" but it...yeah...sorry. Maybe you can pretend this is just a film adaptation of Earth Defense Force 2017?