I would like to give an example to what I talk about when I think about feats being Big and meaningful.
Lets take Cleave as an example; as it is right now it simply allow you to make an extra attack to a creature within reach if you killed a creature with your main attack.
I think that cleave should be something more like this:
On your turn, when you drop an opponent to 0 HP or lower, you may take a 5 foot step and attack another opponent, if you drop that opponent to 0 HP you may repeat the attack. the number of such attack you may do on your turn is equal to your level.
That way, Cleave become the feat that allow you to cleave your way trough a sea of opponents. and it's a feat that grow better as you level.
Warder
Having fewer, more meaningful feats that don't build on each other sounds like a good idea. The issue with it and feats like your cleave is that it's so good, no melee character should be without it. I really do like your cleave feat though, it's cleave, greater cleave and supreme cleave from 3e all merged into one.
The cleave - greater cleave - supreme cleave feat chain isn't the worst type of feat chain. What I don't like is the old requirements for Whirlwind attack from 3e: dodge, mobility, spring attack, expertise. You needed 13 dex and int and it added a lot of complexity and planning needed when building your character.
Instead of feat chains like Whirlwind attack and lots of prerequisites, maybe you get feat points that you could use to boost your feats. You could get 2 feat points at level 1 and 1 feat point at every level.
Cleave:
2 points: On your turn, when you drop an opponent to 0 HP or lower, you may repeat the attack against another opponent adjacent to you (max once per round).
3 points: as above, but up to three times per round.
4 points: as above, but you can take a 5' step before repeating the attack.
Whirlwind attack:
2 points: On a natural 20 you can repeat the attack
3 points: instead of 20 you repeat the attack on 18 or above
4 points: instead of 18 you repeat the attack on 16 or above
Power attack:
2 points: take a -1 penalty to attack to get a +2 damage bonus
3 points: take a -2 penalty to attack to get a +5 damage bonus
4 points: take a -3 penalty to attack to get a +10 damage bonus
The benefit of these self-contained feats is that they make planning your character a lot easier. Not getting 13 int at level 1 won't stop you from getting Whirlwind attack, but not getting it at level 1 will make it take longer to get.