I've been to the British Museum's Vikings exhibition. Somewhat disappointing, to be honest. It was pretty crowded and I didn't think that the museum's presentation of exhibits was too good, either.
It was new when we were on honeymoon in York. The queue was long and tickets had to be booked well in advance, but we'd booked up for it when we arranged our honeymoon travel so we just walked straight in
The same company did a similar exhibition in Oxford, but despite living just outside and working in Oxford, we never went. It was all university history and we're surrounded by that all the time.