Have you tried it? From the feature overview at http://www.codelobster.com/yii.html there are two interesting things: Autocomplete for Behaviors and Controller/View navigation.
Controller/View navigation is pretty straightforward thing. Still useful.
Autocomplete for Behaviors must be something really great. Still I can’t get from example if it works with attachBehavior only or behaviors method of CComponent is also supported.
Just tried the free version,I created an empty Yii project,very straightforward.I tried all the features except the behavior:they work as advertised,impressive stuff.The controller/view navigation is lightning fast,although Yii folder structure already makes it easy to navigate.The autocomplete is lightning fast also,reminded me of my beloved Flash Builder which I don’t use that much now-and I miss it.F1 navigates you straight to the Yii Class Reference online.Overall very nice,not to mention CobeLobster is very light compared to netbeans ,for example,which I currently use.Netbeans I think will be the next IDE that Yii will conquer.Cross fingers.
Only downside:the 100$.
Enough of my ranting.
Samdark I am looking forward to your book,I learn a lot already from reading your forum replies.
Cheers!
Well, behaviors stuff is the most interesting part 
The rest, maybe except views navigation, isn’t so useful or exists in other IDEs.
The main point of NetBeans is that it’s multiplatform, so that you can use the same IDE on different OS…
I constantly work on different platforms (Linux - Windows)…
CodeLobster is only for windows, and that is bad IMO…