I agree with markus, if you're just learning PHP, i'd start off with something that doesn't give you all the code as you type.
But its not just that, is misspelling variables names (or member functions of objects) that waste your time and not so much going to php.net
How about LIVE syntax checks. Know how word underlines an incorrectly spelled word? PHPED from NuSphere does this, among much more.
I didn't pay for it, company I contract for did, but I think its worth the money.
From an ex-Dreamweaver user, the transition was easy. The only thing I did is change syntax colors (Yes you can pick any coloring scheme for the all the languages it supports)
Eclipse is made in java and is slow. Its good for Java, but not PHP so much.
I'm not a salesperson from NuSphere, but I don't have to be to rate their products.
Most importantly, they listen. They have a forum that you can suggest fixes, ask about how to do things and they answer very promptly.
The program has the builtin PHP manual (among others) and saves you time (precious time when you working with deadlines) by doing the syntax check live,
built in debugger, (Full blown debugger for PHP, excellent for large apps)
live syntax checker (gives you a red mark next to scroll bar for those 1000 long line pages), this saved me alot of time because unlike dreamweaver, I didn't have to FTP the file, and run it to tell me I forgot a semi-colon or a parenthesis
By the way, it has support for PHP Documenter. If you document you're classes and put the description for a function (or notes to remember), it shows up in a little tool tip when you use the function.
Support for Smarty templating.
I could go on, but you get the point.
-Dan
PS: if you have any questions and don't want to ask the understandably biased sales people, shoot me a PM.