I know they've gone back and improved them a bit but last time I checked a lot of the subtitles were still like they translated from the original to some random language then to English then back to some other random language before translating back to English again and unfortunately the dubbing is far short of the original audio - doesn't make it unwatchable but loses something for the English viewer who doesn't have a good grasp of Spanish.
Sadly my Spanish is basic/intermediate. I did try to re-watch part 1 a couple of years ago in Spanish without English subs but it was futile, as they talk so fast!!!
Now my Spanish is good enough to understand a lot of it (with English subtitles still on, off course) and it seems relatively accurate to me.
I'm guessing from your comments your Spanish is better than me and i'm wrong on my critique/assessment of the subs! It hasn't affected my enjoyment so far though, in the sense I discuss the intricacies of the show with many Spanish friends and I haven't missed anything from watching the subs!
I've clicked a few links on YT with clips with the english audio, and I think it's terrible just because you lose the passion and emotion of the Spanish Language.
rp2000