I've flown around the Hebrides several times. It remains, in my fairly experienced viewpoint, the best light aeroplane flying in the world.
There are no islands, or airfields, I'd not happily visit or revisit. Occasionally you'll get stranded somewhere for a few days by the weather - go prepared for it, and you'll enjoy that as much as the flying.
Southern central Scotland is pleasant enough to fly through,although no more or less special than much of England.
Eastern Scotland has a few nice airfields, and some quite spectacular coastline to see from the air.
I've not flown myself to the north yet. I've visited Orkney by other means however, and suspect that the flying is as good as the Hebrides.
Talk on the radio, be careful with your nav, don't trust the wind forecasts, think ahead for your fuel, always squawk, never descend below 2000ft agl (or above the nearby peaks) except above an airfield, never be afraid to divert if the weather is getting nasty and you'll be fine and enjoy some of the finest flying in the world.
G