I have a DS in Yr 11 and DD in Yr 11 both doing GCSE Art (DS also doing textiles, DD taking RM). I agree with the posters above, art and textiles are the most time consuming of all their subjects and involve working at lunchtimes, after school and putting in lots of effort at home - working on sketchbooks, portfolio work etc (including quite a lot of written content such as statements of intent, evaluations etc). What they are doing is fascinating, however (and each is very different), and I have really noticed their skills developing, and we have all enjoyed going on family trips to exhibitions and galleries.
DS is hoping to go on to do A level Art and A level Textiles, then a foundation course, with a view to then doing a degree in a design related subject, so he doesn't mind putting in the hours, but it is definitely not a soft option. However, it does make a good contrast to subjects which involve a lot of written work. We have been looking at Graphic Design at A level - it wasn't an option at GCSE - and the work I saw was interesting but I thought the Art was more wide-ranging in content.
The GCSE Art exam consists of, I think, two 5 hour exams to produce a final piece of work - I believe the brief will be given in January, with the exam taken in March. The benefit of this is that it should be over and done with before we get into the intensive revision period for the main GCSEs in May/June.