Meh, I watch a raw from time to time. They're usually for educational purposes (vocabulary reinforcement), but when you think about it, it's not a very good idea for learning regular speech. The vocal inflection is often times highly unnatural.
They're still entertaining nonetheless. I found that watching the raw to Mewtwo Strikes Back was a better experience than watching a subtitled version. In a few ways, I found the movie to be a little depressing, in which the emotion contained within the character development and the plot might have been taken away if it was with subtitles. I guess it's all in your opinion, but it might depend on what you're watching. For example, Jin-Roh would have been fine with or without subtitles, mostly because the dialogue is much more minimalistic than most movies.