Holiday Inn Express is the budget version of the Holiday Inn, so don't expect luxurious rooms or facilities here... but it is perfect for a short stay.
I paid 1400 HKD per night, which I think is OK considering it included WiFi and a light breakfast. The room was bigger than I expected. It was brightly decorated and there was even a sofa. The TV was really small though.
The location is perfect though - right at Causeway Bay. You can walk to Times Square in a couple minutes and it's so easy to get around Hong Kong by the MTR.