I've (Slidey) compiled a brief summary of the pros and cons of each textbook. If you disagree, feel free to discuss it here in this thread. =)
And this isn't an attempt to sell these books. Use your library. It's free that way.
pLuvia: I've updated this thread to make available to all levels of HSC maths and all your suggestions

Content
General Mathematics
Mathematics
Mathematics Extension 1
Mathematics Extension 2
Study Guides
Links
Where to buy?
General Mathematics
HSC General Maths Practice Questions by Topic
Cambridge General Mathematics
Success One HSC General Mathematics
Mathematics
Fitzpatrick 2u
+ This book is great. It's good at all the areas: Good diagrams, good explanations, many question to practice with.
+ The questions are the strength of this text. They cover the entire spectrum of skills which students require and lead you into the hard questions progressively.
+ The harder questions often involve interesting skills which are not taught at a 2u level but would be classified as "component B", of which the HSC must comprise at least 20%. Thus it is worth your while to try these questions.
+ Of all the textbooks, this one is the easiest to cram with.
+ Specimen papers at the end of the book for revision
 No worked solutions.
Cambridge 2u
+ Plenty of questions
+ 3 different levels of questions designed to suit students with varying abilities including development and extension
 Not all questions are useful for practice excercises
 No worked solutions
 Heavier than most other textbooks
Conceptual Development: Maths In Focus
+ This book is excellent at explaining most things and for developing the basic skills for each topic. So if you find yourself struggling to understand a topic, try this book.
 Theory is too simplified
 Many Extension students dislike this book because it is too easy and does not contain many, if any, hard questions.
 If you have the 3U copy it is hard to tell whether or not a topic is part of the 2U or 3U course. A second edition has been published differentiating between 2u and 3u topics
 Examples provided are very simple and usually do not help with harder questions.
 No worked solutions. Some worked solutions
Coroneos
+ Wide variety of questions
 Explanations aren't too great
 No worked solutions
Mathematics Extension 1
Cambridge 3u
+ Plenty of questions
+ Extension questions available
 Not all questions are useful for practice excercises
 No worked solutions
 Heavier than most other textbooks
Fitzpatrick 3u
+ Good explanations
+ Good questions
+ The challenging questions are not always the last ones
+ Speciman papers at the end of the book for revision
 No worked solutions
 Few solutions to graph questions
Essentials of Mathematics, book 2
+ Worked out solutions
+ Good questions
Mathematics Extension 2
Terry Lee Advanced Mathematics
+ Worked out solutions
+ Good set out
+ Easy to understand
+ Review Exercises available
+ Challenge questions for each topic
 Explanations aren't too great
Cambridge 4u
+ Questions are excellent
+ Review exercises at the end of each topic, plus some challenge questions
+ Authors write the 4u Maths CSSA Trial
+ Specimen papers at the end for revision
 Explanations are sometimes not clear
 Answers are not numbered
 Not very appealing
 No worked solutions
Fitzpatrick 4u
+ Questions are good, but not so challenging
+ Explanations are good in some areas
+ Speciman papers at the end of the book for revision
 No worked solutions
Study guides
Understanding Year 11/12 Maths:
+ Easy questions to practice with.
+ Good for cramming
 Questions are TOO easy.
Excel
+ Some challenging questions
+ Has worked solutions
 Just a textbook with less questions to practice on and more examples
 Wouldn't advise for cramming
 May have many mistakes (so watch out!)
Past Paper Collection by the Mathematical Association of NSW for General, 2u, 3u and 4u Maths
+ Has many past papers
+ Great for practice
+ Fully worked solutions for the Past Papers
Links
What maths textbook are you using?
Maths textbooks
The textbook thread (special edition)
HSC Online
Resource Section
Where to buy?
These books are available nearly everywhere here's a list I compiled
 Local Library
 School library
 Your maths teacher

Buy/Sell forum

Terry Lee books
 Dymocks
 Coop shops
 Angus & Robertson
 Borders
 Kinokuniya
 WHSmith
Bookmarks