It's been interesting to watch how this series went from a smaller action movie with a heavy dramatic slant, to basically becoming the epitome of 80's action movie excess. That's not necessarily a bad thing, just an observation. Rambo III is so far removed from the tone of the first film that Rambo takes on the entire Russian army, Troutman joins in for the action, and they even trade one liners and shit. Oh, and Rambo uses a tank to play chicken with a helicopter. Even the nonsensical title (there never was a Rambo II) just seems to perfectly encapsulate how a major studio insults the audience's intelligence in favor of creating a brand. Like it's not a film, it's a product.
It's a little boring in the first half, and definitely a stupid, soulless movie, but I'd be a liar if I didn't say the second half is fun. There's still some sort of pretense of seriousness/relevance, what with Rambo teaming up with the rebels in Afghanistan to fight the Russians (oops! I don't think Rambo meant to pave the way for the Taliban to come into power), but that all takes a back seat to the action.
I've never been a huge Stallone fan, he just doesn't have the track record that Schwarzenegger or Willis have, but having now recently seen all the Rambo movies, I'll give him credit for making a series without a bad entry. I mean, that's more than Van Damme accomplished. Still, his body of work (in action movies) as a whole maybe ties with early Steven Seagal.
This isn't as good as parts 1 or 2, but I still kinda liked it, as an action aficionado. Worth your time if you like this shit.