Agree Fat Buddha.
I enjoyed much of the run yesterday - the support on the course was great and the atmosphere fantastic, and for £30-odd entry fee it offers great value for money...but like you when I finished I had a nightmare with the crowds on the course, and then getting away from the finish and back to Waterloo station.
And like you say, the course seems to be getting more and more crowded each year. I lost count the amount of times I got tripped from behind, elbowed or cut up by runners who were quicker than me (or thought they were - some of them I saw a few miles later struggling!!) haring off up the road - and it wasn't as if I started in a higher pen than I should have. Although the start was a shambles, as others have said on another thread, and as a result there were plenty of people in the wrong start place, and I found the field didn't settle down until the second half of the course.
My main running gripe (and this will polarise the forum readers I have no doubt!) was people wearing headphones - for fecks sake its a crowded marathon - 40000 people are on the course, if you're not looking where you're going, and you can't hear other runners, you will run into them! How many times did I have an iPod wearer run across / into me yesterday!?! Too many times to mention!
On the way home my thoughts were 'never again' and they haven't really changed today. After seven Londons I think it may be time to think of another spring marathon - my brother did Stratford yesterday and whilst it was a tough course he enjoyed it and only 800 or so runners did the full marathon, so maybe next year I may think about that one.