There are many good development tools for php scripting, but this IDE has some features that make it worth to be taken into account. UTF-8 support is the most valuable feature, which will encourage programmers to write strict html code; perhaps in other versions ISO-8859 support may be added, which will be a great advancement.
The editor is pretty easy to use, besides it has many standard features found in other editors like code highlighting, code block collapsing, html elements insertion and others. It also has code template tags and an object browser. In other words, it helps you to write scripts faster and in a well organized manner, providing extremely valuable features when you need to debug a code and pursue a bug.
Although the program is shareware, you can download it and try for free, you can even use it without any restrictions as an unregistered version. But if you want support and updates, you have to pay for it, which is a nice policy. Even though the price is a little bit high, this software is worth every single dollar of it.