IMO, Penguin was a recalculation of PageRank with the basis now being relevant content between linking and linked pages. Base PR seems to be ignored.
SERPs were dropped with the amount depending on anchor text used on non-relevant pages.
Panda's link removal caused massive drops just by removing the spammy linking sites. One of my sites selling software went from 800+ visits a day to around 100.
This site was building links on a 99.99% organic basis.
(Users were building tutorials on using the graphic filters.)
Pre-Panda I was gaining 3500 organic links a month.
Post-Panda I am down to 2400 after everything settled in.
During Panda I dropped to about 350 a month.
I have worked/ am working with a few clients trying to restore their SERPs but it looks like if you got hammered in the SERPs, you best start over with a new domain.
Nothing seems to work, even for primary phrases.