Sure, it's good. But there are other 2nd level spells that are good too. If you're fighting ground-pounders Levitation means you can't even be hit (barring ranged weapons naturally), Scorching Ray is pretty darn good, Melf's Acid Arrow and it's penetration of SR is pretty good, Rope Trick is an almost must have 2nd lvl spell, etc., the list goes on.
If every other spell cast is a Mirror Image to keep them up (and a party of four should be easily doing 4-6 attacks per round) that's alot of spells for defense (and rightly so). A caster typically doesn't have this many to burn unless they be a Sorc or a higher level Wizard. There are more useful spells the caster could likely be casting: such as levitate from melee folk and protection from arrows for ranged. Only two spells and nigh untouchable at only 3-5th level. More bang for your buck there, then they cast spells that are actually offensive in nature. :\
Yes but the look on the caster's face when his mirror image is dispeled with the barbarian nearby...
One of the reasons I like simple 1st level spells like FR-Scatterspray, toss a bag of marbles next to the cast the spell to spray marbles in a 10ft radius. Or better yet just take a bag of marbles and throw them in a wide swath, think the bag of flour to find the invisible guy.