It's not just about the industrial design though. With an asking price of 160 quid, you'd be right to expect at least a half-decent sound too.
You'll be pleased to know the sound quality is rather good, with a warm, natural mix across the spectrum. Rather than go down the Beats by Dre route, the M1s don't attempt to overload you with enough bass to burst your brain, instead offering a more realistic warm and punchy tone.
That's not to say the bass is weak though -- far from it. You still get plenty of wallop and I found they did a great job of handling some of my meatier tunes like the Skrillex remix of Levels by Avicii and Cloudburn by Feed Me, although I did find the mix became a little muddy at times. The bass was deep and powerful, while still allowing the snare hits and vocals to cut through.
They also dealt admirably with the high-end sounds. On Death Cab For Cutie's track Bixby Canyon Bridge, the jingle of the cymbals was clear and well separated, as were the lead synth pads, which were clearly distinguishable against the rest of the mix.
They don't offer quite the level of sparkle I like, but I've certainly heard a lot worse. I would suggest the M1s are well suited to fans of rock, pop and electronic music, but if you want a very open soundscape such as with classical music, you might be better off buying open-backed cans.
The Philips Fidelio M1s offer a very sturdy construction that's likely to appeal if you appreciate stark industrial designs. They provide a strong level of bass without sounding unnatural and bring enough mid and high-end to the table to satisfy all but the most demanding of audiophiles.
At £160, they're certainly not cheap, but they provide a good combination of build and sound quality to make them a worthy option for an upgrade.