I bought this phone because I wanted a compact phone with caller display. However, the display is very hard to read unless you hold the handset at exactly the right angle, in exactly the right light. It's virtually impossible to read the display when the phone is 'on hook' on its cradle - which is precisely when you do want to read it! The display is too small, it isn't backlit, and it's recessed too far behind a curved, overly-reflective plastic panel. It's just too frustrating and awkward to use.
On top of that, the handset is very badly designed ergonomically. The central part, with all the buttons, is convex and sticks out too far. So when holding the handset to your ear, the buttons press uncomfortably against your cheek, and it's far too easy accidentally to press them with your cheekbone. Also, you have to hold the handset very carefully to avoid your fingers wrapping round the edges and also pressing the buttons accidentally. (I've had other buttons-on-handset phones with better-shaped handsets that didn't have either of these problems).
Maybe I could have lived with these niggles if the phone had actually worked, but it didn't. I returned the first one and obtained a replacement, but that was faulty too so was also sent back. The electronics in the phone don't seem to be adequately shielded from the earpiece; all you can hear is lots of crackly noise, making the phone completely unusable (and in case you're wondering: yes, it was definitely the phone and not a noisy line - several other phones plugged into the same phone socket all worked perfectly).
So, this was a phone that promised a lot on paper but failed to deliver. It is badly designed and poorly built. Although some BT-branded phones are very good, the Duet 60 isn't one of them, and I wouldn't recommend it.