It was one of my course books as well, but I think it's aimed at the American market and style of learning/presentation. I much preferred Stroud's "Engineering Mathematics" which was a course book for engineers at my university (I studied physics).
Ouch! Boas is maybe not as inspiring as Feynman. But when you see a copy on someone's bookshelf. It tends to be just as dog-eared and spine-cracked as Surely You're Joking
Another resource I just thought of. While not a textbook per se. Math competition problems from previous years can be very stimulating ;)
