Pros: Warm musical tone, large quantities of bass, fun sounding.
Cons: Lacks detail & clarity, leaks sound.
I decided to purchase these headphones after reading the large thread that was praising them greatly. I was in the market for a budget basshead pair of headphones, so it was a logical decision. As soon as I received them, I used them as my primary headphones for a week, while burning them in during the night.
My initial impression confirmed that the tone was very warm, musical, and colored. They were pleasant and non-fatiguing to listen to, with a very nice soundstage, and were a massive comfort improvement over my Grados. I did notice a large amount of sound leakage -- it was nothing like a Grado's sound leakage, but it was apparent. These are more semi-closed headphones than they are closed. They felt like an improvement over my more expensive, more analytic cans for genres like electronic. I quickly grew to like them. I compared them against a friend's M50s and decided that, although the M50s had a definite edge, the RP-HTF600s held their ground surprisingly well. I decided I liked the headphones enough to warrant purchasing Pearstone Velour Pads for them. They fit very nicely and improved the comfort to a 5 star rating.
Over time, though, I found myself missing the clarity and punch of my more expensive headphones. By the end of the week, I had switched back to using the Grados as my primary headphones and left the HTF600s as my on-the-go/when-the-Grados-start-feeling-uncomfortable semi-open cans. The best way I can describe how they sounded by comparison is that the HTF600s sounded like they were playing through molasses -- the attack and decay was not very quick. When I played very high-paced bass lines, like those seen in Dark Psytrance music, the HTF600s could barely keep up and the notes were difficult to separate. the more technical features of the headphones were very indicative of their price. The RP-HTF600s are no giant-killers, but they brought a lot of value for the price.
Bottom line, for someone looking to try a pair of bassy headphones, these are an excellent starting place. They are easy to drive, forgiving of source, comfortable, and have a musical tone. They offer a high amount of value in the $30-40 price range, but I feel like they begin to start getting outclassed beyond that -- despite the rave reviews of the HTF600, I would not personally buy them again if they are priced outside of that range. I love the returns I got on this headphone for the price, but try to avoid many of the hyperboles offered by the HTF600 fans at Head-Fi.
These headphones no longer get any head time from me anymore, really. The budget headphone market has expanded since these first became FotMs. I still enjoyed the purchase, but I dropped the value score on this headphone from 4 stars to 3.5 stars and the overall rating from 4 stars to 3.5 stars.
Just remember that these are semi-open headphones with some sound leakage and that they are not the absolute highest fidelity for the price. The Monoprice 8323 and the Incipio Forte F38 are, at this time, both technically superior headphones at a lower price.