Here's an article in support:
http://www.ustr.gov/new/fta/cafta.htm
Here's one against:
http://www.thenation.com/doc.mhtml?i=20040202&s=engler
Personally, I don't see much direct benefit to the US. Folks in these countries for the most part cannot afford US goods anyhow -- so "opening up new markets" is not a reason that I can really believe.
On the other hand, US manufacturers need places to go for cheap labor. I'd rather have US manufacturing firms owning plants down there than Chinese ones.
Anyone have thoughts on this?