I'll start by stating that I am replacing an older pair of active noise canceling headphones that I used for 5-6 hours/day for the past four years in varying office environments. The old pair had a plastic swivel attaching the ear cup to the head band which finally broke after about a thousand times (literally, do the math) placing them into and taking them out of the case.As I mentioned I use these headphones primarily in an office environment to listen to music (I'm a software developer) and/or to just block out the constant hum of HVAC systems, etc. I've been reading countless of reviews on numerous headphones looking for something that fits my needs and after much consideration I settled on the QC25's.The main things I took into consideration when looking for my replacement headphones were: comfort, sound quality, noise cancelation, noise leakage, craftsmanship/durability, battery life, case, style, features (wireless/playback control/etc), and price. Here's how the QC25 rates:Comfort - 5/5 - These are the most comfortable non-studio headphones I have ever worn. They are fairly light weight and have a large over-ear design. The ear cups are also fairly deep so there's no contact between my ears and the ear pieces at all. The cups rotate to allow you to wear these comfortably on your head however you desire. The material on the ear cups is a soft foam filled leather that doesn't apply too much pressure to the side of the head (I wear glasses so ear comfort is of utmost importance to me). There is also a foam filled suede material on the top of the headband making the headphones rest comfortably on your head.Sound Quality - 5/5 - Excellent and well balanced. If you're looking for headphones that just amplify the lows and the highs, these are not for you. If you want solid lows, crisp highs and a pronounced mid-range then look no further. These headphones play the music as-is and let you control any equalization you feel is necessary for your best listening experience. I suppose if you're just into thumping base and are listening from a mobile device that doesn't support custom equalization you may be better off with a different brand.Noise Cancelation - 5/5 - The first thing I did when I got these is pop in the included battery and walk into my furnace room (the furnace was running) to see the impact and it was profound. These far outperformed my previous noise canceling headphones (which weren't too shabby). At work I sit near a call center where there are typically 4-6 people on the phone during busier times. There are also heat pump units in the ceiling which hum and buzz throughout the day (especially since the temperatures have been in the single digits the past several weeks). The second I flip the switch on all of the humming and buzzing is gone without a trace. The call center noise is also greatly reduced (I'd say about 70% quieter than without the headphones on) to the point that I have a hard time focusing on any one conversation. This is of course remedied when I turn on some music and the awesome sound quality completely drowns out any remaining distractions. I frequently have colleagues walk up and do jumping jacks to get my attention as I don't even hear them knocking on my desk when I'm "in the zone".Noise Leakage - 4/5 - One of my slight disappointments with the QC25 is the level of noise leakage (the amount of sound that can be heard by people nearby). At a comfortable listening level the noise leakage can be heard from 4-5 feet away. If you like to listen to your music loud, expect people up to 10 feet away (in quiet environments) to sing along with your tunes. I'm currently in a cubicle environment so the closest person to me is about 5 feet away, however at my previous office I sat 3 feet from another guy with no divider so it definitely would have been an issue there (except he wore headphones all day as well ;).Craftsmanship/Durability - 5/5 - I only have a couple pairs of headphones to compare these to but they look like they are made well. The joints and swivels are made with metal parts and are fastened with screws. The headband is made from a metal ribbon surrounded by plastic. The cup internals are covered with a rugged cloth (as opposed to the foam covering which often disintegrates after extended use). The ear cups are a foam filled leather material that seems durable (same style on my old headphones and those lasted 4+ years). Even the cord is made with sturdy gold-plated ends. They flex well and seem like they would last a long time even on larger heads. (I had a friend who ate through headphones due to his large head).Battery Life - 4/5 - So far the battery life on these is acceptable. The noise canceling feature is typically on for 6-8 hours a day and I find that so far I've gone 2-3 days before swapping batteries. I am also using some older rechargeable batteries which probably don't have the same life that they once did. I have not completely drained a standard AAA battery to see how much life you get out of those. The battery life is comparable to my old headphones (which is where the batteries came from) and is sufficient for my needs.Case - 4/5 - The carrying case included with the headphones is sturdy and has a nice look/feel to it. The headphones fold up rather small and fit neatly into the case leaving just enough room for the included headphone cable and maybe an adapter or two. There is an elastic pouch on the back side of the case but it is designed more for storing your instruction manual or thin items (perhaps an extra cable?). Because of my obsessive use of the headphones I own a small USB powered AAA batter charger which fit perfectly into my old case...when my batteries were low I could pull out the charger and charge a battery while my backup was in the headphones...not so with this new case. Fortunately I almost always use the headphones with my macbook pro so I can keep the battery charger in my laptop bag when I need it. Aside from that, the case is very compact and does include a little slot for a spare battery (one AAA is included) as well as an airplane adapter.Style - 5/5 - I own the black design and I like them. I'm not a style buff when it comes to headphones but I certainly don't want some big ugly things on my head. These are sleek with an undertone of teal on the cups and on the in-line playback controller. The plastic is a brushed style and I am overall very pleased with how these look.Features - 4/5 - The only feature I was passively looking for in headphones that these don't have is wireless capabilities. This isn't a show stopper for me, of course, since I came from wired headphones and I am typically always at my desk when using them. Again, I do not use these while walking about listening to music from my phone or music player so I can't speak to that experience. There are inline playback controls which consists of a small (1.25" long) control with three buttons. There is a volume up button, a volume down button and a center button to control playback. A single press of the center button will play/pause your music, a double-tap of the button will skip to the next track and a triple-tap will skip to the previous track. I already have keyboard controls for this functionality but I imagine if listening to a music device (that supports inline playback controls) this would be convenient.Price - 4/5 - Who doesn't want more for less? For the quality and package you get the price is fair. If you're looking for an exceptional pair of headphones with great noise canceling, great sound and decent features this is a great option to consider.Overall - 4.5/5 - I would recommend these to anyone that doesn't mind being wired to their audio source and who doesn't mind anyone within their reach being able to hear what they're listening to. I'm extremely satisfied with my purchase and would buy them again.