I can pretty much assure you that if I were playing a fighter, I would take this feat *a ton*. Assuming that it's on the fighter feat list, my feats would probably be something like this for a human fighter.
H1 - wpn foc: greatsword
L1 - power attack
F1 - cleave
F2 - sunder
L3 - improved toughness
F4 - wpon spec: greatsword
L6 - expertise
L6 - improved toughness
F8 - improved toughness
L9 - improved toughness
F10 - improved toughness
L12 - improved toughness
F12 - improved toughness
F14 - improved toughness
L15 - improved toughness
F16 - improved toughness
L18 - improved toughness
F18 - improved toughness
F20 - improved toughness
With a 28 point buy, I'd start with the following, assuming I didn't want to *totally* min-max down to 8s, or play a half-orc or dwarf, or anything like that.
str 16
dex 12
con 14
int 12
wis 10
cha 10
So, my HP would go as follows:
Level, HD, Con, Con Bonus, # Imp. Tgh., Feat Bonus, Total HP
1, 10, 14, 2, 0, 0, 12
2, 20, 14, 4, 0, 0, 24
3, 26, 14, 6, 1, 3, 35
4, 31, 14, 8, 1, 4, 43
5, 37, 16, 15, 1, 5, 57
6, 42, 16, 18, 2, 12, 72
7, 48, 16, 21, 2, 14, 83
8, 53, 16, 24, 3, 24, 101
9, 59, 16, 27, 4, 36, 122
10, 64, 18, 40, 5, 50, 154
11, 70, 18, 44, 5, 55, 169
12, 75, 18, 48, 7, 84, 207
13, 81, 18, 52, 7, 91, 224
14, 86, 18, 56, 8, 112, 254
15, 92, 20, 75, 9, 135, 302
16, 97, 20, 80, 10, 160, 337
17, 103, 20, 85, 10, 170, 358
18, 108, 20, 90, 12, 216, 414
19, 114, 20, 95, 12, 228, 437
20, 119, 20, 100, 13, 260, 479
Assuming that I got amulets of health per the increasing CON score, which I probably could.
Yep, that's what I'd do. Or at least I'd give it a shot. Meanwhile, I'd rely on power attack, increasing strength, and my greatsword to still put out a pretty good amount of damage. Sunder to destroy opponent's weapons on occasion (a +2 LS takes 19 damage to destroy; against a so-so opponent I'd succeed in hitting it, usually, and by 5th level be doing that much damage every time). Expertise to help my AC in the rare event that I needed it. I'm not sure it'd be the best character ever,or even close, but gosh, I'd sure be willing to give it a shot.