I'm the author of that post. SICP is definitely the book that people most often tell me I missed when they read this. I hadn't even cracked it open at the time I wrote the post, so I didn't feel qualified to comment on it. (I've started reading it since. I haven't finished it yet, but I'd still recommend it to anyone who wants to learn Scheme or functional programming.)

I think that's a book that you can 'read' and you can really read it. By really read, I mean do the exercises.

It makes the book a totally different and more complete experience.

So, this can be a book people read, but not really read. If this makes sense...

SICP is also oft-recommended, and very hard to work your way all through. But even reading (and working through -- that's essential) selective parts is an excellent experience.