Cool, clean, cheap, convenient!
I stayed 2 nights at Cosmo Hotel Mongkok and feel like I made a really smart choice. It is a "boutique hotel" so looks modern with a cool style. The price is also very good and the location in Kowloon makes it easy to get around by train, bus or taxi.
I booked a Superior Room which came with free WiFi and free breakfast. The hotel also has "24 hour check in/out" policy which means you can check in any time and then check out 24 hours later. This is perfect if you have a very early or late arrival time.
Overall, I was happy with the room. Yes it is a bit small but this is common in Hong Kong and especially for a low price hotel. On the positive, the room was very stylish and clean with a TV, mini-fridge, coffee/tea maker and bathroom with a rain shower. The hotel is also 100% non-smoking.
The Cosmo Mongkok doesn't have many facilities (no pool), but there is a gym and shuttle bus to take you to shopping areas. There is also a very good Thai restaurant in the hotel and the prices are very reasonable too just like the rooms.