We enjoyed the extended stay in Edinburgh, which is crazy at festival time. The scenery in Skye was magnificent. Those were two reasons we chose this cruise, and we were happy we did.
One area that I think HAL can do better is their packaged shore excursions. In general we struck out on our own or did a pre-arranged tour. In all cases they were far less costly, more personalized, and in general better, than the HAL tours.
In Belfast we had a private cab from BelfastAttactions for less than the packaged HAL bus tour. The driver, Girard, was very informative and very personable. He had a full history file of "the Troubles" which he shared with us. It gave us a lot more insight into the history than we had picked up from the media. The North Antrim Coast is spectacular and not to be missed, the best parts being off the standard tourist tracks. Girard was also taking pictures with his iPhone at each stop and e-mailed them all to us; a nice touch.
In Inverness we used ocean-links-golf. That tour was again, less costly and far more personalized than the HAL tour. We visited a number of places where the large coaches simply could not get in, and avoided some of the coach tourist traps. Our guide Cyd (in full kilts) was great.
We initially viewed Newcastle as a "throwaway" but found the city's Georgian and Victorian architecture quite interesting, and its riverfront (and bridges) enjoyable. Newcastle was a pleasant surprise. On the other side of the coin we were disappointed in Stirling Castle. While there's a lot of history there the castle itself it a bit of a downer, and the rush hour traffic though Glasgow made for a tedious trip. From a castle standpoint we did, however thoroughly enjoy Cawdor (which by the way has a very good small cafeteria); and Eileen Donan, while not particularly historic, is a lot of fun and has a spectacular setting.
By the way, if you have some extra time in South Queensferry (Edinburgh) walk the five minutes into town. It's cute and has some nice pubs and galleries.
As a final note; try to avoid the internet access on the ship. It's quite expensive and very slow. If you buy 30 minutes of time expect to do about 10 minutes of work at best because of the connection speed and the technology they use. McD's and Starbucks on shore have WiFi, and for the price of a cup of coffee you can get a lot more done.