My time spent reading the Forge of Mars was mostly spent agape in sheer stupefaction at how not good the novel was.
The characters were simply unreal. They were generally consistent, at least, but in the way that a flat, stereotypic impression of a character is. The villain was literally a moustache-twirling 100% evil ex-Soviet General and his little dog. And he was less cringe inducing than the main characters, Tai and Yvonne.
The story also suffered from extreme tonal dissonance. Is the story grim and serious? Is it sexy? Is it profound? Is it goofy? Is it deadpan? Is it HILARIOUS? The Forge of Mars is all of those! And thus it suffers from extreme tonal whiplash, where you have a breakup and serious discussions of relationships and future career plans followed by a character slipping into the Museum of Bureaucracy to escape someone chasing him, and running through office dioramas and jokes about government employees.
Additionally, the world was very confusing. There was real AI, nanotechnology, nanotech 3d printers, and regular no-big-deal space travel, to name just four big developments. And society did not change in the slightest as a result. It felt completely unreal to have that level of technological development, but have everything else feel like the early 2000s.
The dialogue was not enjoyable, and the scene descriptions generally went on too much and were not of importance. This dragged down the plot, especially when combined with jarring scene transitions between the multiple viewpoint characters.
Now, the bit I enjoyed: There are some cool and enjoyable bits with alien robots later on, as in B movie enjoyable. Still, if you want something like that, you should check out a Keith Laumer book, or one of Fred Saberhagen’s lighter Berserker books.