PHP has a rather strict no-BC-break policy for minor releases. As such the 5.x series improves the language mostly through additions. I think that's good. PHP has been missing a number of things that are now present.
However that doesn't work forever, at some point you need to clean up some of the old stuff. That's why a PHP 6 release is planned in the near future (i.e. somewhere in the next three years ^^).
The very first programming book I bought was "PHP6 and MySQL5" by Larry Ullman. I bought that one specifically because I had another job (career, really) and I knew it was going to take a while before I really got into programming and I didn't want to buy a book that was going to be out of date in 2 years. That book is now 6 years old, out of date, and PHP6 is still not released. Maybe 6 is just an unlucky number with Perl unable to make that goal as well, but either way I'm not holding my breath.
I've since moved on to more well thought out languages, though PHP keeps pulling me back in. I'm currently having to support a CI app that hasn't had a line of code added to it since 2008, and the only thing I can say, even though I appreciate the language and how far it's pushed the web, I'm glad it's no longer my go-to language of choice. Keep PHP5 around for a while so apps like this one can continue on, but PHP6 is _LONG_ overdue.
The goal for PHP6 is basically to provide good unicode support (strings internally as unicode etc.)
However due to problems and internal conflicts the effort was stopped a few years ago and there has been no progress since.
If this goal hadn't been stated PHP 5.3+5.4 would probably have been PHP 6 (they have some major new features). Core API cleanup never has been (and it doesn't look like it will soon be) a goal for a future release, unfortunately.
Same here. Larry's a great author. I got started with his books years ago. He definitely makes Web dev feel more approachable, which is invaluable to a newbie. I believe Patrick Collison from Stripe also got started on Larry's books (for some reason I recall a conversion on Twitter or the like about this).
Sounds like if PHP6 is going to be cleaned up and break backwards compatibility then it really needs to be named PHP+ or named differently so that the less informed nonfollowing developers understand it's not just PHP5 plus some more stuff and therefore it's not backwards compatible.
However that doesn't work forever, at some point you need to clean up some of the old stuff. That's why a PHP 6 release is planned in the near future (i.e. somewhere in the next three years ^^).