Once in a while I'll use blind-fire, but I've found that when I blind-fire when enemies know I'm in that section of cover, they kill me by shooting my hands. As a previous poster stated, it's a "when the situation presents itself, use it" kind of a feature; on a few levels with a long corridor that I know always is being covered, I'll latch onto cover and with an SMG, blind-fire 1-2 second long bursts before unbuttoning from cover and finding another route. Sometimes I'll get a kill (or three) but usually I'll just suppress or cause the enemies, if any, to be more cautious in that area.
I'd recommend only using blind-fire with an SMG/automatic weapon (semi-auto rifles I frown upon using blind-fire with, but it's still more effective than with a bolt-action rifle). However, I have had some luck with bolt-action rifles where I had no escape route and I knew enemies were rushing towards my section of cover, so I blind-fired a couple shots with my K98 and killed enemies directly ahead at roughly 8m. With teammates supporting you/attempting to suppress the enemy, blind-firing can be the tipping point for causing the enemy to become suppressed or put more lead down field to cause your enemy to slow their advance. Also, blind-firing grenades is a fantastic thing, though some pieces of "standing" cover don't allow you to actually throw the grenade down a hallway or past the cover you're at, but those pieces of cover are few and far between.