I have a love-hate relationship with the Artemis IV system. Which side is dominant depends mostly on who I'm playing as. If it's a regular military with supply lines, the Artemis is one of my favorite pieces of 3050 equipment, since it in essence increases the power of the launcher to the next higher level. LRM-10's become LRM-15s, LRM-15s become LRM-20s, etc. Moreover, as I usually have a bad case of Hellbie dice, anything that adds pluses to my rolls is welcome.
If I'm a mercenary, however, they're one of the first things I get rid of. The problem is not so much the effectiveness so much as the cost: LRM munitions are expensive enough as is, and Artemis-guided munitions are twice that. In other words, it's a cost in dead-weight tonnage on my mech or a cost in ridiculously high ammo bills eating into my profit margin.