There are a few things are are *SOOO* subtle in Xcode. You need to know them of you will hate Xcode2. Thanks to my buddy Jeff Kahn and some good IM – I learned these tricks. Each thing easily has wasted several hours to a half day for me. But once you know them Xcode2 becomes more tolerable.
I am having fun with Objective C. I like the message pattern. It is fun to send messages to things. I worry a *lot* about memory leaks though.
On to the critical bits.

Autocomplete: While typing, when there is an underline, you can press Escape to see possible completions. I love autocompletion but after four days- I still had not picked up this subtle clue.
Editing a .h file and using it in NIB: Only use Classes -> Create files *once* – for iterative development, simply edit the class interface file (xyz.h) using the editor and then save the file and drag the .h file into NIB. Then NIB will know about new or changed outliet and actions and you don’t have to use the (yet another hard to use GUI) FileMerge program to retain your local instance variables and commments in the .h etc. Once you have dragged the file in, you can wire up the new outlets and actions using NIB. This makes iterative development FAR cleaner. Lesson: Use Xcode2 as the IDE – use NIB for layout and wiring – not code editing :).
Also see my prior post on how to set a delegate for an onScreen control.