I am certain some people would call a feat useful that others describe as crappy. I, for example, find those skill-boosting feats pretty useless. Sure it's nice to have them, but there are so many better choices for a feat slot.
What feats do you have in mind?
I don't think the skill boosters are useless, just too weak to choose unless they are requirements for something good. They could be rewards, but they aren't lame rewards by any stretch.
Archer's Bane - Way too narrow. Like in all games, narrow advantages have to be powerful to be considered over broad advantages.
Armoured Stealth - You already wasted a feat on Stealthy, how much specialization do you want so that your chain shirt can be worn? Anyone with Light-Footed (which is awesome) isn't going to care about this anyway.
Blind-Fight - At least when it's useful, it could be useful. Still way too narrow.
Carouser - Everybody in our group wants this as a freebie feat because it's flavorful. But, nobody would ever take it with a real feat slot.
Demon Killer - Great name. I've been tempted by this because of that and because Will saves suck for a lot of characters, but the reality is that it doesn't do much and it's obnoxious to be constantly sinking feats into improving Will saves when a barbarian with a code of honor can put feats into ubercleave, uberinitiative, or whatever. One of the supplements has a way better feat for Terror checks, as well.
Exotic Weapon Proficiency - It should come with some sort of bonus like +1 to hit and +2 damage. I wouldn't even bother making this a reward feat. I'd just make it a flat reward for someone's character concept or experiences since it doesn't really do anything you couldn't do by playing a specific race or a barbarian.
Far Shot - Like your typical PC could hurt anything with unpoisoned ranged weapons anyway.
Greater Critical - Has the problem anything does with increasing the chances of crits - killing stuff isn't that hard. Once you need something like a crit with your standard weapon, you might be fighting something immune to them, immune to your weapon (demons), etc.
Great Fortitude - As much as it's nice to make massive damage saves, this is way too narrow for such a paltry bonus. At least Lightning Reflexes helps initiative and Iron Will helps with something that's really hard to help if you play certain classes. It's painful to take those two since there are much stronger feats in most cases and the gains are modest, but I'd have to be pretty desperate for something to do to take Fortitude with a PC.
Anything involving sundering or disarming - It's so much easier to just kill things. The times you want to unarm someone are so much fewer than the times you could just waste your enemies.
Anything involving archery - Archery is just so weak. The number of feats you sink into doing things productive is absurd compared to just taking Power Attack and Cleave. I wouldn't want my character to be only good at one thing in combat like archery (yet that's precisely what my first Conan character did and still wasn't useful).
Anything mounted - I just don't envision too many narrow Conan campaigns. This has similar problems to the favorite terrain abilities of classes. Just too many situations when you have an ability you can't use.
That's glancing through the main book and ignoring some feats I'd only take because they were requirements for ones I might actually want. Take a look at some of the supplement feats; they are so ridiculously specialized and often do so little when they do trigger. As options for NPCs, okay, whatever. But, why can't feats make some effort to be balanced so that PCs don't all look alike?
BTW, regarding seeing "Improved X" feats, I'd expect Improved Feint to be taken frequently because sneak attack damage is so good in Conan. Improved Grapple is better for NPCs as a way to screw over players, but it should be useful often enough for PCs as well.