Animal Liberation

I was a bit hesitant to read a 40 year old book on the subject of animal liberation, even knowing it was a classic and seminal work. It holds up, Singer's arguments are persuasive and compelling.
My main complaint- why I'm not giving it 4 stars, I read the 2009 edition but it really felt like no substantial updates had been made since the 1990 edition. Singer frequently talks about progress made in the late 80s, new developments in the last 15 years (since the book was published), etc, but little to nothing is said about what happened between 1990 and 2009. The basic premise still holds true and the arguments are valuable but I wish the figures were a bit more up to date.