Mixed Feelings
Granted, the luxury hotel market in Houston is somewhat limited, but I was pretty disappointed in the Four Seasons. The valet staff were very prompt and friendly, so I do want to give special thanks to them because they made a wonderful first impression. 
The lobby is nice. There is something very retro about the chandeliers, but it somehow works. Overall, I would say the lobby is quite impressive and in line with the purported star rating of the hotel. The exterior, however, is very very 70's. There is absolutely nothing they can do about that, but you cannot help but notice it.
The desk clerk was quite pleasant. I cannot remember her name, but as with most people at the hotel, if you were interacting with them in person, they delivered top-notch service. My biggest complaint about the service, and it is a big one, is that they NEVER answer the phone promptly. I literally would let the phone ring 30+ times, still with no answer. So then I would try housekeeping, the concierge, room service, anybody...same thing. For a five-star hotel, it is pretty unacceptable for this to occur. One time - sure; things happen. This problem, however, existed throughout my entire stay. 
As others have noted, there are certain elements that make the hotel appear quite dated. The elevators are ancient and should definitely be at the top of the list for upcoming renovations. The tracks on the drapes in the room were also quite old. The rooms were pleasant, but not extraordinary. I had to switch rooms, however, because the first one had a very awful musty smell. We were then moved to a room on the level with the pool. It was okay, but it felt very dark. Also, the pool area looked a bit worse for wear. I can imagine how luxurious this place must have been in its prime, but that prime has certainly passed. 
One thing that I find absolutely unforgiveable about this hotel, though, is the ice machine room. They need to remove all signage relating to the ice machine and make guests call to have ice delivered. I had the misfortune of going to fetch my own ice, and I walked into a room that was filthy, covered in trash and clearly (hopefully) not meant to be seen by guests. I was so shocked. For any hotel above 1 star, I would expect more.
The location is great, and you are able to get out of the city quickly, but I was surprised at how dead Houston is at night. Clearly, this has nothing to do with the hotel, so I am not trying to make any connection there; I was just surprised. I would think it might be wiser to stay near the Galleria if you are looking for something other than just a business stay.
All in all, the stay was "ok"; nothing really wow'ed me about this place, so I guess that disappoints me, but I tend to find that to be the case with Four Seasons and Ritz Carlton properties. They rely a lot on name recognition and branding, but they always seem to fall flat for me, both in terms of service and design/aesthetics.