Posted January 7th, 2013, 07:13 PM
Yes, the hotel is within walking distance of the terminal, but it is still off-airport. That means the OP will have to exit the secure area of the airport, go through immigration and claim luggage. He/she may then be able to re-check bags for the onward flight, or has the choice of keeping the bags and re-checking them later.
Some airports have a hotel within the secure area, where you can stay overnight, between flights. If the onward flight is within a certain number of hours, you do not have to reclaim your luggage, but can have it checked through to the final destination. (I've done this in Singapore, but don't know if teh same situation exists in Hong Kong.)
There's a risk of this confusing several things.
The hotel is not "off-airport" in the conventional sense, because it remains on the airport campus and (like most on-airport hotels) is accessible by foot without the need for a transfer service. Many more airports have such on-airport hotels than have transit hotels within the sterile area. By definition, the market for a transit hotel's services is much more limited, and it can't do many things that on-airport hotels typically do, such as host meetings between people who have flown in and people who are based in the city where the airport is.
A transit hotel cannot, by definition, allow you access to your checked baggage because all checked baggage areas are outside the sterile passenger area (for obvious reasons).
However, you do not necessairly have to reclaim your checked baggage even if you decide to leave the sterile area and go to a landside hotel (whether on-airport or off-airport). In many cases, the airline will through-check your bags so you do not have to collect them between flights, even if you choose to exit the sterile area.