It's so rife with errors and conjecture that I find it hard to take very seriously. I haven't watched the second edition in its entirety but the parts I saw made claims essentially similar to what I had seen in the first version so I assume it is similarly full of crap.
Many of the claims have been refuted many times over the last five years. There's a fair amount of sarcasm and anger but
this addresses the video in tedious details.
This Popular Mechanics article attempts to debunk the most common 9/11 myths, most of which appear in the Loose Change video. Here's a
blog focused on debunking Loose Change.
Personally, the conspiracy posited by Loose Change is so huge, malignant, and convoluted to strike me as patently unlikely on the face. Combine this with the evidence in counter to specific points (such as the claimed lack of airplane debris at the Pentagon crash site when in fact there is plenty of evidence of debris at the site) and I'm barely intrigued.
Unfortunately, I expect that in another 10 years it will have grown to Kennedy assassination proportions in terms of general acceptance.