Definitely the most entertaining of the ones I've seen. I enjoy the first one for its epic hilariousness and didn't much care for the second. Watched about 5 minutes of tokyo drift and couldn't take it and skipped the last one.
As an over the top car-related action film it was actually pretty great. Yes it was way un-believable and over the top, but that was part of the fun. The plot wasn't terrible and though it was long I think they kept the pace up pretty well. I had low expectations, as did my girl, but we both actually really enjoyed this one. Had some good laughs even. Would definitely recommend if you have any interest in FnF films.