I'm here on a cash stay as a non member, so I can't comment on the quality from a Hyatt perspective, but here is a brief review strictly from a customer stay perspective.
1. Location - perfect for us, as the in-laws are a 5 minute walk away, the MRT is also a 5 minute walk, our bus stops are also a few minutes away - so location wise, for us, it's perfect. If you're a tourist visiting, it's also a good location given the access to the MRT red line (101 to points north, including the hot springs district), and a reasonable walk to the Sogo locations and Zhongxiao Rd for shopping and restaurants
2. Service - while this isn't a 5* hotel in the service department, I would call it friendly and helpful and very competent. This isn't the Four Seasons and does not pretend to be - and finding a resort of that caliber is very rare in Taiwan anyway, but for the very reasonable price charged, I cannot complain at all about the service.
3. Breakfast - there is a breakfast buffet now (no longer menu service), and the offerings change very little daily. It's a fairly basic offering, certainly quite a few choices, but no where near what you'll find in a larger hotel like the Grand Hyatt, or one of the Marriott hotels. There just isn't the space for it - which is why this is a "small" luxury hotel
4. Rooms - the rooms are tight, but not overly small. We have plenty of space for two, and the room furnishings are modern and well maintained. Our room has floor to ceiling windows in a "juliet balcony" design (doors do not open). Our one complaint is the asinine design of the showers - with no door, using the regular or rainfall shower heads can end up flooding both the bathroom floor, and the entire room if you're not careful.
5. Amenities - I did not see a separate concierge desk, but I believe concierge services are available. There is a restaurant for breakfast, afternoon tea and dinner, and a weekend brunch. There is no fitness center, but we noticed every single door in this hotel weighs about 1,000lbs and can take 2 people to open. The front door, and our room door - you really need to throw your weight into them to open, so that has become our backup fitness routine.
All in all, we're very pleased with our stay so far - half way through our 9 nights.