I have worked with SP1 and found it not to bad,
SP2 was, I heard, 'not to be used'
On SP3:
I found a bug on contouring operations when using HSM and/or slowdown options if the operation has only one guide curve.
Multi axis Sweeping will not 'remember' it's tool axis if you switch to a catpart. You must replay it.
I had some problems with roughing operations that could not recognize the current material condition. I had to create the roughing operation earlier in the machining sequence, lock the operation then move it in it's good position.
The cutter definition of a taper tool is not good. The E value is not taken into consideration.
A cycle statement is transformed into GOTO's in a tracut.
The RAPID button does not generate rapid in some cycle syntaxes
If you NoShow stuff in a catpart while you're in a catprocess, you can't Show them from the catproduct or from another catpart.
Center Graph does not work from a catprocess (it may not be a bug, but it certainly is a pain...)
Even if you have saved your work, you will be prompted to save for ever when you try to close the models.
....

I have'nt tryed SP4.

SP5 is out but I have'nt tryed it yet...


With SP1, I've encountered a bug that I never dare trying to check if it was fixed. Back then, if you CUT and PASTE an AXIAL operation, it was sometimes impossible to save your catprocess.
I took the habit of using COPY and PASTE then DELETE the operation or save the catprocess before and after the CUT and PASTE.

Good luck

Those are the types of things I am constantly
running into.  I also have quite a few problems
getting the macros to work like they are supposed to,
it seems that no two modules are configured the same.

It's good to know I'm not losing my mind and that
my complaints are valid.  

Thanks for the information.