I've had these headphones for a few days now, but I've been wearing them a great deal in that time. I use them primarily at work---I'm in an office with anywhere between 8 and 12 people at any given time, so being able to focus on my work and cut out the background noise is important to me. Overall I have a few key points:
1. The sound quality itself is quite good, and for a wide variety of music. The sound is crisp and the speakers handle the bass without crackling or generating a lot of fuzz.
2. As previous reviewers have noted the noise cancellation feature is lacking. Although, I guess it depends on how you define "95%." Low frequency sound is cancelled out pretty well, but high frequency sounds are barely touched. Just using the noise cancelling feature and playing no music, I can still hear conversations in my office relatively clearly. The major difference is that people sound a bit more nasaly. If you're looking to take these headphones on a trip then I suspect how satisfied you are depends on where or how you're traveling. A train might be alright as most of the noise is relatively low frequency. However, if a lot of people are talking then my previous point. A plane ride, however, when combined with the stereotypical crying baby, might work out less well. Again, the high frequency noise from crying children will probably not be cut out all that much by these headphones.
I've tried out the Bose headphones in stores prior to buying these, and I can safely say that Bose's noise cancellation far superior and cuts out most of the sound around you. That said, there is also the cost difference to take into consideration.
3. As for the build and battery replacement, I haven't really found this to be a problem. Yes, it's behind the left earphone, but it comes off easily and the battery slot is right there. The general build of the headphones seems to be quite solid as well. Although, I will say that compared to the Sennheiser headphones that some of my coworkers have, the headphone itself and the cushioning could be built a little larger so as to make it a little less cramped around your ear. While they are definitely over-ear headphones, the fit is a little tighter around the ear than other brands (e.g. Sennheiser, Bose).
Overall I'd say this is a solid pair of headphones with good sound quality and a pretty comfortable fit. But the noise cancellation feature is definitely overstated. If you travel a lot and are concerned with the noise issue, then you may be better off splurging on the Bose headphones. Yes, I'm sure that you are paying for the name in part, but I suspect you'll be greatful you spent the extra money if you spend a lot of time on a plane.