FC1 was awesome. Best looking game of its time. The Trigens were odd but didn't ruin it IMHO.
I didn't play FC2 or 3 so I can't comment.
However, I traded in a few games on Friday for FC4.
One of the best FPS games I've played.
The graphics are just mind blowingly ridiculous. You can stand at the top of a bell tower and look out of thousands of acres of landscape and see all the details. It's crazy. But then you look at the ground and it's equally detailed. And that's from a console.
I actually really love the crafting stuff. TBH I've spent most of my time just wandering around hunting animals and collecting plants. Not because I didn't know what to do just because I like exploring
Yes you can buy ammo but you can also collect it from people who drop it when they are killed. ATM I can carry 180 rounds of assault rifle ammo and it usually takes about three well aimed shots to kill an enemy. There are some heavy troops that are harder to take down but I've only seen a couple so far.
Also, you can heal yourself without healing syringes but it takes longer and you can't heal as much in one go. You can buy syringes fairly cheaply though and they're scattered around houses and huts and stuff. The crafted syringes also give you extra bonuses which I first thought would be useless but actually they're awesome. There is a "Hunting Syringe" which will automatically mark enemies and animals that are nearby. At a higher level they also improve your stealth walking etc... And that's one out of the four different crafted syringes.
TBH though, I just love flying around. I grabbed a hang glider and jumped off the side of a mountain. Then bailed out and descended with my wing suit and parachuted into the camp I was aiming for
Another thing. It's huge. So far I've been playing 8 hours. I've captured 2 outposts and 3 bell towers (these remove Fog of War from the map). And I can see another 20+ bell towers on the map. I've maybe uncovered 5-10% of the total map. In a car it currently takes about 10+ minutes to drive from between my two furthest safe houses.