He had one line - but he got to go the premiere and party in Leicester Square, even though they had a sort of "tradesmen's" red carpet which joined up with the main red carpet at the steps! 
I did spot him, as well as hearing his line (well, what mother wouldn't spot her son - even in the crowd?!) and was very proud to see his name in the list of credits at the end.You get warned about this kind of thing when you go into acting: you might be at the National Theatre one week and then you could be working in Argos the next...
But what about the film - this is supposed to be a review, pg, come on, get a move on.
Well... to be honest I thought the script was pretty dire - though the special effects were impressive. It was a bit like Pirates of the Caribbean without the attraction of a witty script (and Johnny Depp). We saw it in 3D, but I gather this was a bit of an afterthought and I don't know how much of a difference it really made - many of the 3D trailers we saw before the film were much more impressive! Poor old Liam Neeson was in a dreadful costume which made him look like someone from Saturday Night Fever and most of the (mainly very impressive) cast had to deliver some shockingly cliched dialogue. Definitely style over substance.
The best "creature" or character was Pegasus the flying horse - that really was impressive I thought, especially in flight.
Interesting that he was the good versus Ralph Fiennes' bad - like they were in Schindler's List (must get that on dvd too).