We stayed 4 nights in Jan 2012. The hotel really is an oasis of calm compared to the chaotic frenzy that is Kathmandu during the day time. The room was nice and modern. Breakfast buffet was great, but the rest of the food for lunch and dinner was a bit over priced compared with the restaraunts that ring the Boudhanath temple only 5 minutes away by taxi.
The Hyatt is a bit further away from Durbar square than the other 5star places, but really wasnt that bad of a drive to the main places. We enjoyed seeing the everyday sights along the way. We hired a guide we found through trip advisor for US$80 per day with a car and driver. He wasn't that great but took us by car to all the major places we wanted to see including Nagarkot to see the sunset against the Himalayas, which I would definitely recommend.
One thing to remember is that in Kathmandu the power goes out EVERY night at 6pm. If you are out walking the street at this time, it gets a bit eerie, but I never felt uncomfortable. However, this also means that a lot of the restaraunts shut down by 8pm (including those I mentioned at Boudhanath), so just plan ahead if you want to go out.
We took the recommendation of the concierge and ate dinner one night at the Dwarika hotel's Krishnarpan restaraunt. They do a 6, 9 or 22 course meal of small portions (which was the same general idea at two other places we went for dinner) of Nepali cuisine. Atmosphere is nice and it was the only place I saw anyone in the entire city wearing a sport coat, although we had been out site seeing all day and were in hiking boots and jeans. Dinner for two with drinks was about US$120, which is fine for a normal night out almost anywhere else, but definitely at the high end in Kathmandu. Food was enjoyable but was the typical fare in most places we ate. They ask you to book a day ahead as they do things like printing your name on the menu and give you a parting gift. Overall enjoyable and it is almost worth it to see the grounds of the hotel.
I would definitely recommend the Hyatt for a comfortable stay in Kathmandu. However, we also took day trips to Bhaktapur and Patan. Bhaktapur was a much more relaxed and enjoyable town to walk around in. Looked like there were many nice places to eat and plenty of hotels. As an analogy, I would say that Bhaktapur is to Kathmandu as Siena, Italy is to Cairo.... It really felt that drastic. I am not sure what the power outage situation is there, but my opinion on seeing the Kathmandu valley would be to stay in Bhaktapur and do a day trip into Kathmandu.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC