Hello all,
This review is written from the perspective of somebody who has spent a lot of time looking for good, cheap, cans - and I've used these good, cheap, cans for 5 years now. I've owned cheap IEMs, Over-ears, On-ears, Earpods, and speakers. On the other hand I own a pair of Zensor 3s and MDR-7506s, and in all of my experience I've never encountered as solid a value-for-money ratio.
For 25 euro you can purchase a new pair HD201s in a number of retailers, I can highly recommend them. Let's start at the beginning:
Packaging: A box, some fabric.
As one might expect from such a cheap headset, the HD201s have very underwhelming packaging. Given that, it's perfectly acceptable - the headset sits inside a cardboard box wrapped in a soft foamy fabric. I would assume that with the lightweight nature of these cans the protection offered should be sufficient to protect them from blunt impacts, and stop the cans getting scuffed. Fine for shipping of any kind.
Build: Bog standard, but very well thought-over.
These headphones are built with cheap-plasticy materials, there's really no other way of saying that, they don't feel or look premium. But to Sennheiser's defense, they've committed no cardinal sins. The plastic casing is matte, making it immune to fingerprints and quite scratch resistant. The colors are plain (silver and black), and don't run or fade. There are also no points of extreme weakness anywhere through the design. Sometimes the extension struts that allow for the cans to be extended or retracted can be snapped, I've experienced this a number of times over our 5 year run, and I can offer two bits of advice regarding this weakness: 1) Don't sit on your headphones - I've done this many a-time, and each time those struts snapped it was under my own weight 2) Using hot glue or epoxy resin to reattach the cups almost always works and holds. The cable is long enough for use for just about any application, is coated in soft (but plasticy feeling) rubber that leaves it durable, easy enough on the eye, and comfortable to have pressed against your body. You can find a lot better at slightly higher price points when it comes to sheer build quality, but If you treat these nicely, they will last, and look okay too.
Ergonomics: Not sleepers, but not in any way offensive.
The HD201s are decent to wear, but that's it. Until worn in they clamp a little hard, which sucks because the ear cups are fairly shallow and the pads aren't fantastic. Pleather and foam. The reality is that they don't hurt, and I have sensitive ears with hella annoying ear ridges

. They hold onto your head through headbanging, and I've hiked with these through rain, sleep, and snow, they're no clouds floating on the ears, but there's little to complain about.
Sound: Best of category, by a mile.
The sound out of these cans is what makes them so remarkable. It's balanced, with clear separation between high, mid, and low frequencies - which is a lot more than can be said of 98% of headphones at this price range, and that's not where it ends. They do sound decent, even in comparison to my Zensors and 7506s, they're much less detailed than those two offerings, with softer treble, and weaker bass.
The mids don't provide much intimacy or subtlety, but they're reasonably musical and rounded - listening to the Gorillaz - D-Sides for example, you can still appreciate the mastery behind Spitting out the Demons, and the various remixes of Kids with Guns. Listening to low vocals, acoustic guitars, pianos, and violins such as - The National - The Alligator (A decently hard album to reproduce due to it's harmonic cacophony of instruments) once can separate, and appreciate each instrument, all of which are portrayed forgivingly. The mids aren't juicy or detailed, but they're enjoyable to listen to - and that's the primary objective of a 25 euro headset. Bang on Sennheiser, budget done right.
The aforementioned treble is a little soft, but present - non-sibilant, and easy to listen to. It strikes that difficult to find balance in similar low-end offerings between just not having anything up top, and the "we hope we've made your ears bleed" trigger happy treble approach. In short, the top-end offers musicality and balance, and while mixes can be left sounding soft when listened to on higher-end offerings and then compared with the 201s, there's nothing there to complain about at this price point whatsoever. Probably the greatest strength of the 201s in their price point, higher frequencies that can cause some mixes to be fatiguing and sibilant are forgiven for being over-zealous, but aren't muted to obscurity.
This is rare and valuable, don't overlook it.
Bass. Well, these aren't for bassheads, but they're also not lacking in a way that feels totally unfair. The bass response is well controlled, decently low-reaching, and generally proportional - but it's quiet. Recessed to just about the point of complaint, it's not rare for bass heavy mixes to sound slightly underplayed on these cans. I think people make too big a deal out of this in this one instance however as in my *considerable* experience most decent all-rounder cans in this price point have either no bass whatsoever, or bass floppier than dying carp. The bass provided by the 201s is present, audible, and controlled. This makes them head and shoulders above most other options - but it'd be nice not to have mention it's recessed nature at all. I wouldn't consider this a deal breaker at all, the bass is there, and can be enjoyed in all mixes - if you're expecting bass that leaves your jaw dropped open, you're expecting far too much out of 25 euro cans.
Needless to say, these cans are low-impedance and will run fine with mobile devices. This review is written on experiences with a pair of 201s that have now been broken in for 500ish hours.
Conclusion:
These cans thoroughly trounce the majority of competitors, and some headphones far above their own price-point. The key to this isn't mind-blowing bass, jaw dropping detail, or stunning good looks. It's the fact that these cans are very well thought out, and then produced en-mass. They avoid all cardinal sins when it comes to packaging (Melt on packaging anyone?), build, or ergonomics - holding a strong 'good enough' on all of them, and on top of it they sound much much better than their price-tag would indicate (I actually had a few days back around 2013 where I got to swap between using 1st gen Beats and the 201s, the 201s beat them into the dust at a fraction of the price).
I would happily recommend these to any man or woman who was looking to spend under 50 euro on headphones.