The GECK is not a slow tool unless your trying to build world LOD, have a weak computer or have something on the system horribly misconfigured.

The GECK is one of the most powerful game editors ever released to the public, I can find None that are as robust and sophisticated in my experience. That may be simply because TES4/Fo3/NV are RPGs and thus are very complex by their nature, and the GECK is the actual tool they used to build it (minus 1 or 2 things like lip sync). It has a steep learning curve, but once over that, you can do just about _anything_ that you put your imagination too.

Unfortunatley there are currently no good Full tutorials on how to use the GECK. Bethesda made some Excellent YouTube videos that will teach you some basics, and the WIKI as WillieSea pointed out, is a great resource when your stuck on something or need to fully understand something. At some point a more comprehensive manual will be made by someone I'm sure.

Miax

the GECK is very user friendly.

It's just very picky about its friends.


Honestly though it is really fiddly in a lot of places, and there are shortcuts that would speed things up if they added them in (I'd love a wizard that automatically opened the script, enchant, explosion, projectile, ammo and then finally item windows for me when I'm making 10 new rocket weapons).

But it's a developer tool, they're not users like you and I: they're power users. They are GECKing 6-10 hours a day for a year, so they see the tool differently. It's very intuitive to them I'm sure after a week of making rooms, and I'm equally sure when it comes to crunch time to get the master program files out the door and to the publisher they're reciting shortcut keys in their sleep (if they even get any sleep that week).
after you've made your fourth or fifth family of ammunition I'm sure that by the sixth you're on autopilot.