Some user error checking (such as script error messages) are kindof included in the GECK but you need a small .dll file and an injector to fix them, and that was provided within a few days of the game's release. It's also ridiculously important for developers, either internal or external. Most of the other problems with the GECK have nothing to do with User Error Checking, such as the lack of the dictionary database being included in the download even though they've already got one from F3, the way the render window doesn't always display all of the objects it should, and the lack of a havok sim or lipsynching software. The user error checking stuff is extremely minor compared to those complaints.
I had said in different post elsewhere - - I think that our current NV geck release musta been put out as being the best of what they had available for us at the time. They are busy peeps right now. The alternative would have been doing what they did with FO3's geck which was waiting until some time after the game release, and holy [censored] did that svck for us.
It seems likely that they will send us another GECK later, one which can show script errors on its own and they'll remember to put the lexicon file into the zipfile.
The missing lipsync generation functionality, that one I donno about. If I had to guess I'd say some licensing issue had cropped up or, they themselves do it differently now? Or maybe they do it the same way and it is equally svckage all around. Can only guess.
I managed to live without the script syntax checker for a while, it was only a bit ago that someone made a version which worked on XP. Now, the checker really feels like a luxury instead of a necessary tool. kinnda interesting how that worked out.