This very entertaining version of the Merlin story is ably acted by its all star cast of John Geilgud, Sam Neill, Helena Bonham Carter and others.It is PG rated, but there are some scenes which I think would not be suitable for younger members of the family and so it would be advisable for parents to watch beforehand if there are children under the age of 12 involved.
In this storyline, which follows roughly the Arthurian legends line as is usually seen, there are a couple of variants. Queen Mab and the Lady of the Lake make regular appearances because Queen Mab and is at loggerheads with Merlin. She also dislikes the Lady of the Lake, who is her sister. One very odd thing is that Merlin gives Excalibur to Uther and then tricks Uther into putting the sword into the stone amidst some rather entertaining animation scenes – I've never seen King Uther being given Excalibur before, it's much more usual for Arthur to find the sword in the stone or to hear about it being in the stone upon his coming of age, and to go and be the only one able to pull it out because of who he is. Disney, by the way, also do this remarkably well in their animated film, The Sword in the Stone.
There are other surprises; Sir Galahad makes an appearance as Sir Lancelot's son as a boy, whereas you normally first see him when he appears at Camelot (with Arthur still alive but in this case the king will be long dead before Galahad is ready to become a knight) and takes his place at the Siege Perilous. So they have switched things around quite a lot. However, the main elements of the story of King Arthur are followed more closely. There is plenty more in the film that is also followed well, though I didn't like the way Mordred's arrival and the exposure of Guinevere and Lancelot's relationship was handled.
All that said, the film is well acted and while one or two of the animations are a little dated most are great fun. It does of course focus on Merlin's love with Nimue, and Queen Mab gets a little unnecessarily nasty to people at times.
I did notice once or twice that there were glitches in my screened viewing of the film, as if there had been breaks for advertisements which were no longer there. However, the whole thing played perfectly well and I do remember it being screened on TV over two evenings one bank holiday weekend some years ago.