We went last Christmas when DS was 7 and he loved it. It is surreal, but rather wonderful I thought. Nicely old fashioned with lots of mime and illusions and the snow's fantastic as it falls in the auditorium.
If you can, sit in the first bit of the stalls as at the end there's masses of daftness with huge inflatable balls which they bounce round over people's heads. Bit pricey, but worth it if you can. We were a way back, but walked down into it all and joined in anyway.
Don't want to dripfeed, but my goddaughter is visually impaired (but has some sight) and the performance I want to go to is audio described with a "touch tour" beforehand in case anyone has any guidance on that aspect in particular.