I bought the HD598 for 200 bucks. I had to have quick delivery because I was leaving America soon which accounts for the relatively high price.
I don't regret the buy at all because I think they sound fantastic. People say they lack bass? I think this is quite a warm headphone, and low bass is punchy with great quantity - not too much and definitely not too little. However, I DO use a well adjusted Winamp equaliser which may compensate for the loss.
I think these sound fantastic with all genres of music except metal, because they just can't attack the music well enough.
Despite the big arguments over amped/unamped, I was using a FiiO E7, but sold it recently - it's a cool gadget, but quite unnecessary. I really won't let anyone tell me otherwise now haha When I buy some higher impedance phones I'll invest in an amp, but these can be powered really easily, and sound fantastic straight from the laptop.
For films and TV they are fantastic because of the great soundstage.
These phones really are the full package (except metal), perform VERY WELL and are extremely affordable.
Plus you need to look at the next headphone up in the Sennheiser range - the HD600/HD650, and then you have to start investing in a good amp and probably a better source as well. So it really is a bargain because you can buy the headphones alone.
If you have 165 dollars, and want an affordable solution which performs very well in all categories, I think you would be foolish to not consider these headphones. However, it does come down to personal taste, and I'm not the most experienced audiophile so I can't compare a lot hehe, but clearly I'm very satisfied.