Pros: Clear mids and highs, a comfortable over ear design
Cons: Lows and highs become overshadowed by supremely clean mids.
Some of the cleanest mids you'll get for the price point. Possibly the perfect entry-level cans for music lovers who want a neutral sound signature.
Bear in mind that most AKG cans are not bass-centric. For bassheads, the K240s may turn you off. Surprisingly, I've grown accustomed to the lightweight bass that the K240's offer. Sure, its bass may be overly mild, but you'll hear the rest of the soundscape with a clarity you will not expect. I listen to these cans with the Cowon J3 which appear to give the K240's more "oomph". However, if you want the kind of "punchy bass" that audiophiles talk about, look elsewhere.
Omnia - The Fusion
Dash Berlin - When You Were Around
Outside of bass, the K240's are amazing. I fell in love with the mids, especially after the first month of burn-in. When I introduced the K240s to Adele, it immediately replicated the songstress's warm register with ease. Of course, the K240's struggled with Whitney's five-octave range, but it wasn't too shabby really. It was at this point that I understood the K240's. The K240's manouvres soundscapes with steady agility, and uses that same technique to tackle both the low and high registers.
Adele - Someone Like You
Whitney - I Have Nothing
Whitney - I Will Always Love You
One other thing I'd comment on is that these headphones are miraculously comfortable. After 2 hours of usage, I almost forgot I have them on. They are surprisingly lightweight.
Note that the K240's require a driver. DO NOT pair them with your smartphone. I have owned them for a year and mostly pair them with the Xonar Essence STX and Cowon J3. My library is mostly FLAC which I play on a non-EQed Foobar2000.