I personally think the SCAR some of the best sights in the whole game. They don't block much, unlike the M4, M16, maybe ACR, and so on. I find myself holding my sights off center while watching something more often than not on other guns just because they visually block whatever area I'm trying to watch.
But I definitely agree that the SCAR is overrated. It was pretty much the only gun I used way back when, before I prestiged for the first time, and I would have swore by it. But I got bored, and started branching out, and while it's still a great gun (it plays the role of a long range AR very, very well), there are many other guns that are just better than it in other ways, and you can do well with other guns too.
The SCAR is still a powerful AR for range though. Its two problems are its rate of fire and clip size.
Edit: Isn't the SCAR the only highly-accurate 40-30 gun in the AR lineup?
M4 - accurate - 30/20
TAR - not accurate - 40/30
FAL - not auto - 50/35/30 (?) forgot
FAMAS - burst - 40/30
M16 - burst - 40/30
ACR - accurate - 30/20
F2000 - not accurate - 40/30
AK - sway - 40/30
Am I missing one? Anyway, the SCAR is popular probably because of it's damage per bullet (not that damage per bullet is the end-all of how good a gun is, just saying) and it's fully auto while still being accurate. The only other ARs that are as accurate as the SCAR are 30/20.
And by accuracy, I just meant how well the gun comes back to original position after firing each bullet. No recoil, etc, you guys know what I mean.