Critical Mass surely differs in style and impact from city to city, so
it's hard to make a general judgement. The one closest to me is in
Santa Monica CA, and after doing one of them I won't do another.
The problem was the same thing I found during the 60's (of which I am
a grizzled veteran): whatever the stated purpose of the event, what
it became was a whole bunch of people getting off on their sheer
numbers, and enjoying the power to be pains in the ass and get away
with it.
Sure there are lots of bike-dangerous drivers out there, but the
chance of any of them being the ones inconvenienced or angered by
Critical Mass is very small. There are a lot more clueless drivers,
but what does it accomplish to [censored] them off, except to potentially
turn them into bike-dangerous drivers?
Besides, I have better ways to get myself off than in large groups.