I was testing some stuff. Almost every app is working fine, all the gtk´s of course, just some strings are missing. The terminal works fine too, the man pages well... I just found one page translated, I am a little perverse so I did:
# man man
That was the only man page in spanish, I will search some man packages on the net...
The non-gtk apps needs extra packs, some ones are easy, like oo or firefox. The gecko browsers, once you export the LANG var the update system do the job, but seems like you need to reinstall the hole app, no lang pack found atm. Opera has lang packs easy to install, just cp some files on the proper location.
Some surprises: gambas2 is translated, thunar, the rigth-click menu with the exeption of the custom actions added by vl.
So, looks like we need just a few steps.
Curchunflo, looks like all the apps you need are there, Abiword and Gnumeric are well translated, you need to install the spell packs only, as Caitlyn said. The browsers, like I said above, opera is the easy one, the others you need to spend a little more of bandwidth.