1. Uses the Delphi language - Delphi as a language is pretty nice to use. I particularly like how you are forced to declare your variables at the top of a function, it keeps your code cleaner. However, I would say that you should be able to declare your variables at the top of any section of code who's visibility is different from others. Case in point. If you are inside a "for" loop, you should be able to declare a variable that is accessible from only within the "for" loop. Current Delphi standards say that even though your intent is to only use this variable within the "for", you must declare it at the top of the function, where it is accessible to the entire function.
2. Debugging - From my previous experience with Visual Studio, I was happy to see that CodeGear had debugging facilities that were just as strong as Visual Studio.
3. Wysiwig editor - Again, from my previous experience with Visual Studio, I was happy to see that CodeGear had a wysiwig editor that was similar to Visual Studio (believe me, I've read all the stuff about MS gutting Borland's development team to form .NET and C#, so I understand that there are similarities in the platforms and IDE's). My only complaint about the wysiwig editor for both Visual Studio and CodeGear RAD, is that there are components that have no visible display, but can be added to your form's gui anyways. Case in point, your data access components (TClientDataSet, etc.). To me, the display editor should be kept pure, and if the IDE wants to show you a graphical representation of non-graphical components, it should be on a separate screen, not intermingled with your display widgets.
4. Heavy use of Win32 API - From experiences with poorly documented 3rd party widgets, I try to stay as far away from 3rd party add-ons as I can. The only time I will use one is when the widget is so awesome that it solves a problem perfectly for me.
5. Usage of .NET - As far as I understand it, CodeGear is one of the only IDE's besides Visual Studio that can write code to .NET's CLR.
6. How similar it is to Visual Studio - Yes yes, I know the history. Delphi is the father of C#, CodeGear RAD (or whatever it used to be called) is the father of the modern Visual Studio. Still, the 2 IDE's are so similar that I could pick up CodeGear RAD and hit the ground running.
The main reason why I am so critical of CodeGear RAD, is because I have heavy experience with Visual Studio, .NET and C#, so I can see where CodeGear RAD falls short. It is only natural to compare the 2 platforms, given how much history they have together. Here's my feelings about Visual Studio vs CodeGear RAD summed up in a pic.