The HTC U11 carries a beautiful stunning design. It uses what HTC calls an "Optical Spectrum Hybrid Deposition". The rear part of the phone is made of layers of highly-reflective minerals that makes the rear cover not just very reflective, but also changes the reflection like fluid with every moment you take. This is a similar reflective design as the HTC U Ultra. Although one of the main disadvantages of this design is that it easily collect fingerprints, it's still looks absolutely unique among all the other finishes I've seen in recent smartphones. No doubt that HTC wanted to make the U11 look really unique as befits a flagship smartphone.
The HTC U11 also carries a symmetrical and slim design (7.9mm). It has a 3D glass on both the rear and front sides, which make it feels like a clamshell, beautifully wrapping and hiding the powerful tech inside in a very pure an elegant manner. This is why I like those type of designs. They are like hiding the complexity of the phone and just making it look so simple, pure and natural. The 3D curved design also makes the U11 more comfortable to hold in the hand and provides users with secure holding.
HTC is not the only and the first company who embraced this stunning dual 3D curved design. Nowadays, if you see one, you know that you are looking at a very advanced smartphone device. It's like a stamp of quality and HTC made sure that when you go to the store and see all those new devices, the HTC U11 will stand apart from the rest. I also think that the physical interaction using the squeeze gesture also creates a better connection between the user and this very personal device.
Here is a great video by TechView.me that made a good video showing the HTC U11 design and how the colors are changing as you view the phone from different angles.
The HTC U11 definitely gets a high score when it comes to external design.