I did my GCSE's about 7 years ago now, but I know the format is pretty much the same. The lessons are more coursework and practical-based than they used to be; less focus on exams (that's not to say you don't get any exams....)
Most kids do between 9-12 GCSEs which for me meant about 6-7 exams and the rest coursework. To be honest, at the time it feels like the most stressful thing in the world but in retrospect it really wasn't.
To get into college (not the same as in America - in the UK college occupies the 2 years between school and University) you only need 5 GCSEs at grade A* to C. According to the league table entry of my old school:
here ->
http://www.dfes.gov.uk/cgi-bin/performancetables/dfe1x1_04.pl?School=3944037&Mode=Z&Type= [nofollow] Around 40% of kids achieve this every year - and my school was a very poor state school. The better schools can expect high 90%.
Once you reach college, your GCSEs become superceded by your A-Levels, so in reality once you leave school (providing your going into higher education) your GCSEs become worthless virtually straight away.
As for the quality of the GCSE... I personally think they are a high quality. British education system is quite well-respected around the world, and I certainly haven't felt out of place with my American, Australian, Spanish and Swedish colleagues at work. Of course, you only get out what you put in...