I do think its about expectations, and mine (like MissSD) were very high given the amazing Italy trip we had taken the year before. Scotland was really good, but here are my thoughts on where ABD could make improvements:
1. Add a Scottish Adventure guide
2. On day 2, spend more time sightseeing in Edinburgh. Our particular group didn't get to go inside Holyroodhouse and I would have liked to see all of Edinburgh Castle (not just the crown jewels, which is what you get on the last day - its nice to have dinner there, but I really wanted a full tour of the castle).
My advice to is to ensure you spend 2-3 days in Edinburgh beforehand to really see the city and its environs, otherwise, you'll really miss out.
3. On day 3, the description seems awesome (and this is where the itinerary description is widely different from reality), but you sit on a bus for 6 hours with little/no historical commentary, etc. We had lunch at Fort William (with no explanation why it was such an important place), and at GlenCoe, you're given a couple sentences about its importance, but no real insight or opp for photos.
We went to Aileen Donan castle, which was pretty, but I wish the tour had gone to Stirling Castle and Wallace Monument instead (we passed right by it on our way out of Edinburgh). This IMHO is one of the most important historical sites to see there (its like going to Paris and skipping Versailles, and seeing Fontainbleu instead...its nice, but not the most historically significant thing to see).
4. The other days in Skye and Lewis are amazing
5. Rothiemurchus estate is also wonderful, but we started that day at around 10am....I really would have liked a tour of Inverness (I don't go on vaca to sleep - I'm happy to leave the hotel by 8am and do more stuff). We barely had a description/overview of Inverness, and its such an amazing city with lots of history. Also, Culloden battlefield is skipped over which was a critical site for the Jacobite movement. If we started the day a little earlier, and left Rothiemurchus just 30 mins earlier, both an Inverness and Culloden tour would be possible.
6. On day 8, ditto on my comments about sitting on a bus for hours w/no historical commentary. We passed through Aberdeen, and the guides weren't going to give any commentary until I nudged them to do so. That said, Dunnotar castle and Balmoral are wonderful to see.
Because you asked where the tour fell short of my expectations, that's what I'm focusing on in this reply. Please don't read this as the tour is terrible...it is not. Its quite good, but falls short of historical context...so I give the tour a "B" grading, where I would give Bella Italia an "A".
If you have the right expectations set, I think you'll have a great time (and you can adjust your pre/post days to cover additional things to do). We're going on the Central Europe tour next year, and I see the Prague part of the itinerary is extremely light...and having now been to Scotland, I know to add many pre-days to do everything I'd like to do!
I'm a big fan of ABD, and I hope they took the feedback from Scotland to craft the Norway trip to strike a balance of both movie/historical elements.