Back in the pre-video age if you loved a film rather than having home media or oldies channels was for kids to by a comic based on the film from Gold Key or Dell. Now, Gold Key and Dell weren't exactly renowned for groundbreaking material or high artistic pretensions, largely being concerned with instead profitability. Guess what IDW did while the first Transformers film was in the theatres even though it would be out on DVD officially within months (and illegally before that). Go on, fucking guess.
The job of adapting the film fell to Kris Oprisko, one of the founders of IDW - check his fucking CV, though: it's like a list of everything awful about shit licence-renting comic companies. Well done to him for finding a book that Simon Furman wouldn't write; amusingly the artistic counterpart of such jaded hackery in 2007 was former Energon penciller Alex Milne, still several years from working on a book anyone liked - this was shortly smooth-talking conman Pat Lee had told him we would totally be paid for his Dreamwave work but if while he was waiting he could draw a few pages of Cyberforce and not put his name on them that would be great.
So broadly it adapts the film itself, though it's clearly based on a shooting script and maybe a few stills, though basically none of the composition is anything like it is on the screen
Pat Lee's gullible flatmate Alex Milne has a largely unsuccessful tilt at drawing. There are some notable bits left in that were cut or not filmed for the movie - Sam actually has a stab at explaining to his dad why he got arrested by the police; Barricade is decapitated by Optimus Prime seconds after Bonecrusher meets his fate, and Megatron seems to consume Jazz's spark after killing him.
There are also a outright few changes - some for the better. Notable ones include the almost total excising of the dodgy hackers subplot; Maggie is reduced to a cameo, while Glen isn't in it at all. It's Jazz who walks into the power cables at Sam's house, and not Ratchet; Sector 7 are a bit nicer to Bumblebee; Bonecrusher and Barricade jump Prime at the Hoover Dam, which seems to be right next to Mission City. Indeed, the whole Mission City battle is much quicker - the Autobots and their allies are immediately attacked by Starscream and Brawl/Devastator (who isn't named) - the latter pounces straight on to the crippled Bumblebee, and is then taken down by the Autobots alone (though Bumblebee still delivers the final blows from a tow-truck). Optimus then faces Megatron immediately. The battle between Optimus and Megatron is less complicated and more even, with the Autobot encouraging Sam to force the Allspark into Megatron's chest. There's also mention that a nuke is dropped on the Decepticon remains after they were dumped at sea. There are lots of little changes too, plus chunks of the film are chucked out or compacted due to this being 88 pages, and the film being 144 minutes long.
None of it is really any good. It starts off quite nicely, as the compressed nature of the adaptation meaning some of the dull stuff from the first half of the film is junked, but it gets messier as it goes on. To give him his due, Milne isn't bad at drawing humans, especially compared to Don Figueroa (the fact that no-one really looks like their screen counterparts is a necessary drawback, due to IDW not being allowed to use likenesses of the actors, what with the cast being famous professionals, and IDW being a tinpot little company who run entirely on renting other people's creations), but he begins to struggle when Transformers begin turning up. This is something of a problem.
The fight scenes are outright terrible - while the kinetic energy of the live action would be beyond all but a few artists, the decision to render them as narrow portrait-orientated frames for the most part makes them cramped, allows no sense of scale and would probably be impossible to follow if the reader didn't have decent working knowledge of the film. Plus all the jokes and most of the fun is surgically removed by the downright clinical script. There's no need to buy this, or even really read it if you get scans from somewhere.