I just returned from Aberdeen a couple weeks ago. First, a nice way to travel up there from London was the overnight sleeper train, the Caladonian. Thanks to DT's advice this was a enjoyable alternative to flying, it has many stops in Scotland so something for almost anyone going there.
The city of Aberdeen itself I felt, had quite a bit to offer. The Euro was being played then and very lively crowds gathered outside to watch on screens or in pubs. I hit the Grosvenor Casino right by my hotel a couple times as well. While not dozens of restaurant options, there were quite a few modern places and of course pub food. I did visit what was apparently the first Mackie's Ice Cream parlor in the city center. I didn't know the family was from the area and buy Mackie's in the grocery store internationally.
Overall, I felt Aberdeen was a nice small city which probably due to competition from St. Andrews/Highlands/Lothian gets overlooked. Played Royal Aberdeen and Cruden Bay. Loved the quirk of CB as everyone does who plays there, similar to a North Berwick which is a good compliment. Royal Aberdeen was a wonderful links, played on a relatively calm day. I hit the ball well for me and just couldn't score as the mistakes led to losing a ball in the gorse which was lush.
So why doesn't Aberdeen get more attention or priority for visitors? I would surmise that if you are taking your first trip almost all visitors want to go to St. Andrews. For the savy visitor probably Lothian or Highlands comes as your second trip if you are staying in Scotland. The entire UK/Ireland gets bundled together for visitors probably and you go where the golf is, with so many great options Aberdeen has a hard time competing with those. However, I agree with Ben in that you will have a wonderful time yet.