I watched this to accompany my study of the play version of The Tempest and found it excellent both in terms of acting and content. Unlike many modern adaptations, this was virtually word perfect to the original and I could follow it in my book whilst I listened, which I found really helped it to sink into my memory.
The acting is very believable, with Hordern playing an impressive Prospero, which really embodies every side of his personality. The supernatural element was not made cheesy with too many special effects, but was simply and sparingly brought in to help you get a grasp of it's significance.
The only criticism is that it does seem slightly dated now and is not so suited to a general modern audience for that reason. However, I find that of very little importance and that this is a great adaptation to watch if you are studying the play or are a fan already. There is not a huge 'wow' factor here, as modern Hollywood could probably provide if picking up on the mystical elements of the play, but the BBC have made a sound and true to the book version which I would highly recommend.