Teach Yourself Delphi 4 in 21 Days
This book by Kent Reisdorph reminds me a bit of Teach Yourself C++Builder 3 in 21 Days (also written by Kent). Not a problem, of course, it's just that some chapters give me a bit of a "deja vu" feeling. The book gives a solid introduction into Delphi 4, with chapters targeted to a beginners audience. One chapter is slightly different, and that's the one on ActiveX and COM (which is not a "beginners subject" in my view), where the book does into somewhat more depth. A 14-Days edition of this book is probably shipping with Delphi 4 Standard (as usual), but if you want to start programming with Delphi 4 Professional, then this is certainly a good book to "teach yourself Delphi 4" (although you don't have to do it in 21 days exactly - take all the time you need: by the end of the book it'll be worth it).
Delphi 4 Bible
Unfortunately, I haven't received a review copy of Tom Swan's book Delphi 4 Bible, yet. However, from what I understand, it's a book for an intermediate audience, where Tom shows how to take advantage of Delphi 4's software development capabilities in different categories, including graphics, animation, database management, the Internet and more.
Delphi 4 Developer's Guide
We missed the "Delphi 3" edition of the Developer's Guide by Steve Teixeira and Xavier Pacheco, but they're back with Delphi 4 Developer's Guide. Both former Borland (or Inprise) Delphi R&D members, they know Delphi inside-out, of course, and if you read this book you'll know what I mean. The information is in-depth, and targeted at intermediate to advanced level Delphi programmers who want to get beyond the basics.
There's one thing about this book that I don't like: the book contains of almost 1200 pages in print, but also another 500 pages on the CD-ROM only. And these are not "bonus" chapters or "extras", but a real part of the book. The main reason must be cost reduction (for the publisher), and you can print them from the CD-ROM, but it just doesn't read as good, and certainly doesn't feel as good as the real thing. The same thing happened with C++Builder 3 Unleashed (also by SAMS), and it appears as if this is a new way to publish "big" books. So, be aware that you also need a printer and have about 500 pages to print if you want to read the entire book.
Mastering Delphi 4
Marco Cantù has done it again: Mastering Delphi 4 is a big book that reads like a novel. Originally targeted at just about any level, from beginner to advanced, Marco has now skipped some of the beginners material from (the previous edition of) this book, replacing it with more advanced material. A rough estimate would state that about half the book is rewritten especially for Delphi 4, and the end result is indeed somewhat more advanced than the previous editions of Mastering Delphi. All text in this 1200+ pages book is actually printed, and there isn't even a CD-ROM included!
Note that for a truly advanced work, Marco has written Delphi Developer's Handbook (also by Sybex), which was written for Delphi 3 but will probably not have a Delphi 4 edition (other than some updates on his website).
Delphi 4 Unleashed
Let me give you a warning here: I'm a bit biased towards this book, because I wrote a chapter for it myself (about Delphi 4 Web Modules, or WebBroker as they also call it). Part of my (huge) chapter was cut in the editing cycle, but you'll be able to read some of it (a big data-aware example) exclusively in the UK-BUG newsletter.
Apart from my own chapter, I can only tell you that Charlie Calvert (working for Inprise Developer Relations, and very closely following the Delphi and C++Builder R&D teams) is writing truly in-depth "Unleashed" volumes for both Delphi and C++Builder, and this one is no different than the rest.
This time, SAMS also put chapters on the CD-ROM, but paid a little bit more attention to which chapter: they're usually the "left over" ones (from last edition) or indeed "bonus" chapters. But you still also need a printer to read the entire book...
For more book reviews (on Delphi, C++Builder, JBuilder or general (internet) programming), check out the special book review webpage or specific reviews of Delphi 1.x and Delphi 2.x.