aimed shot is defintiely worth having, and it has it's perks. if you're in an instance, or in PVP, and your fighting a priest or paly combo with a warrior, rogue, whatever the case, hit him with an aimed shot. the point of the shot isn't so much the added damage, but the 50% less heals that a enemy will receive from a priest or paly on their side will make a huge difference.
i'm a level 70 hunter, and in all honesty, i never use it when i'm fighting something other than a group where i notice a healer alongside of a dps class. problem is, the casting time. here and there i'll be fighting another hunter in PVP, and i'll get off 4-5 shots by the time they hit me wth one aimed shot. even if it hits for 1000-1500 damage, doesn't matter, i've already hit him with 4-5 shots of 5-600 per hit, got a sting already on him, and my pet is beating him down and keeps delaying the casting time. just for the sake of it, get into a duel or PVP match, and try shooting a hunter with an aimed shot just for the sake of seeing what happens. you'll take so long because it keeps getting delayed by the pets and the hunters hits, you'll be 50% or less by the time you actually get that shot off. so while it has its benefits of course, it's not a shot that you should be using too much. like i said, there's certain times when it'll be great, but when it comes down to it the cast time is brutal and makes it a pain in the neck to deal with.
i'm a level 70 hunter, and in all honesty, i never use it when i'm fighting something other than a group where i notice a healer alongside of a dps class. problem is, the casting time. here and there i'll be fighting another hunter in PVP, and i'll get off 4-5 shots by the time they hit me wth one aimed shot. even if it hits for 1000-1500 damage, doesn't matter, i've already hit him with 4-5 shots of 5-600 per hit, got a sting already on him, and my pet is beating him down and keeps delaying the casting time. just for the sake of it, get into a duel or PVP match, and try shooting a hunter with an aimed shot just for the sake of seeing what happens. you'll take so long because it keeps getting delayed by the pets and the hunters hits, you'll be 50% or less by the time you actually get that shot off. so while it has its benefits of course, it's not a shot that you should be using too much. like i said, there's certain times when it'll be great, but when it comes down to it the cast time is brutal and makes it a pain in the neck to deal with.