Superbly located modern chic - and friendly to boot
Entered through a calm, plant-lined and covered promenade off Crosby Street, Mondrian is in a superb location on the border between Soho and Lower East Side - posh shops in one direction, a more gritty side to Manhattan and the bustle of Chinatown in the other!
After a long flight from London, our bags where whisked away from us before we'd even checked in, to magically reappear in our room shortly after. The hotel is clearly aiming for cool vibes - staff are in jeans and tucked-in shirts, there's a fair amount of blue neon lighting, and Dawn Penn playing in the lifts (or 'elevators', if you prefer). But it also has a friendly vibe - everyone we came into contact with was helpful and sincere. 
The rooms are minimilistic, but not to an extreme level. They are white and bright, with touches of vivid blue. We were on the 14th floor facing east, and the floor-to-ceiling windows let in a tremendous amount of light in the mornings especially. We were also facing Lafayette Street, which isn't nearly as quiet as Crosby Street. However, being relatively high up minimised street noise. And let's be honest - if you're staying in the middle of Manhattan, it's never going to be deadly silent. 
The toilet situation: many reviews have mentioned the glass door to the bathroom in the rooms, which seems to bother some people and not others. Here's the lowdown:
- The door to the bathroom is indeed glass, but it's frosted and you can't see through it - even with the light on in the bathroom. However, it's not a tight fitting door, so if you really tried you could see through the cracks around the edge. 
- The door is not sound-proof
- The bathroom contains the shower and toilet
- The basin is outside the bathroom, in a tiled area off the bedroom
All of this didn't really affect us - although it is unusual, and may be slightly off-putting if it's the first time away with your partner!
Rather than the usual hotel folder full of check-out times etc, everything was on the room iPad. There was strong wifi in the room, which we got complimentary but which I believe there is normally a charge for. Not quite sure why we got it for free - perhaps just ask nicely!
In conclusion, the Mondrian is a well located, calm hotel at a fair price - and if (when!) we go back to NYC, we'd certainly look this place up again.