My wife and I previously stayed at the National Hotel in December 2008 and returned for a few days in July 2010 following a pleasant initial stay. Unfortunately, this time we struck a period of very hot weather and discovered to our surprise that there is no airconditioning in the rooms (NOTE: This appears to be the case with many hotels of a similar rating in Frankfurt). Whilst the hotel promotes the fact that windows open, our room tended to resemble a furnace most of the time, despite being provided with a rotating desk fan. Upon opening up the windows, we were greeted with the constant sound of both vehicles and people which was far from ideal. To compound matters, the mini bar fridge barely worked and didn't keep things cold.
One of the "bug bears" from our previous visit was that the hotel bar was only spasmodically opened and disappointingly, nothing has changed. We were given complimentary drink vouchers on our arrival and when attempting to utilise on a Saturday evening was told the bar would not be opening.
Notwithstanding the above comments, the hotel has some positive features in its favour by way of being located close to the main rail way station and offering good sized and clean rooms, along with the fact that a first class breakfast (comprising both a hot and cold selection) is generally included in the room rate. Furthermore, staff are pleasant and free internet use is available in the foyer or accessible via wifi from your room for a nominal cost.
In summary, the hotel is certainly not 4 stars as promoted but is more akin to 3 star hotel offering reasonable value for money. At the end of the day, if one was considering staying at this hotel in summer, it is probably a matter of weighing up the "pluses v's minuses", although I would certainly recommend requesting a room away from the main street to try and minimise noise, should the windows require to be open.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC