SICP is the one text I wish I'd known about when studying computer science at uni. When I finally discovered and read it, it was a truly eye-opening experience and revolutionised the way I thought about tackling problems and designing software. It may have been around for a while, but the ideas presented still hold water today.

As others have mentioned, the linked version has some definite improvements over the web version provided by MIT Press [0], which doesn't have particularly clear diagrams.

In fact, MIT Press does have an alternative version with larger diagrams [1], but the footnote links don't work.

Do also check out the 1986 Abelson and Sussman lectures [2] that accompany the text. Those two present the course in such an interesting and (dare I say it) fun way.

And for those who have already watched that and are curious, I've recently uploaded a 2004 version of the lectures to YouTube [3]. They're sourced from the SICP iCampus site [4], which is another fantastic resource, though I find the way that site presents the lectures to be a bit annoying. Completing the problem sets is a good way to check your understanding, though!

[0] http://mitpress.mit.edu/sicp/full-text/book/book.html

[1] https://mitpress.mit.edu/sicp/full-text/sicp/book/

[2] http://www.youtube.com/playlist?list=PLE18841CABEA24090

[3] http://www.youtube.com/playlist?list=PL7BcsI5ueSNFPCEisbaoQ0...

[4] http://icampustutor.csail.mit.edu/6.001-public/