We docked a £12-15 taxi ride away from the City, but the driver was excellent talkative and knowledgeable. There was a £4 shuttle bus laid on, but the service was erratic, to say the least.
Reykjavik is exceptional. Tiny for a capital, but picturesque, very 'cool'and somehow sure of itself. The weather was gorgeous, hot sun we were told was the norm for all of June & July this year, and we had a great time.
The National gallery is small, but interesting, and the Icelandic museum was amuch grander affair, with the permaanent exhibition telling the story of the country from 874 well worth a visit (and about £4 entry fee).
It is expensive, but I think everyone knows that, so make sure you eat on the boat. We had a small beer in a bar for about £4.50 and food, drink and tat were similarly highly priced in comparison with Britain.
Do go though - lots to commend the place for.