There's a lot to be admired by Far Cry 2: the environmental mechanics, the introduction, the lighting effects, the gritty and exotic atmosphere... but to me it was not a fun game. Not in the way that Far Cry 1 was fun.
This is the main thing that made it not fun for me, lol. There really is no point in partaking in random combat in the open-world. It's always better to run away or sneak past them. Fine in a stealth game, but FC2 didn't have great stealth mechanics beyond crouching and staying far away from enemies.
All the other FC games are stealth games too, BTW. The later FC games made it even more explicit, with bonuses for never setting off alarms and so on.
I stopped playing the series after 3 because they did feel that way, but without gameplay features I wanted to match. Games that rewarded stealth, but without stealth-specific mechanics like you'd find in Hitman or MGS. It feels like the writers want to encourage stealth but the game designers didn't. At least for 1-3. The original I definitely accepted it more because of the era.