Rated 4 out of 5 stars

First if you are located in China mainland, then you cannot download it because at the moment it is blocked by the Great Firewall of China.

I've downloaded 0.3.8.xpi and found
* it doesn't work on my tb-2.0.0.14 (iBook/ppc/Gentoo Linux), the freefrom form doesn't appear when composing message (even after it is enabled). 0.1.7 worked for me however.
* the "improvement" from 0.1.7 to 0.3.8 seems to be:
1. added a warning to stop user sending emails without subject line;
2. remind user for missing attachment.

Both "improvements" are useful but I think they better be in separate plug-ins. The Unix tradition principle of programs should "just do one thing and do it well" seems also apply in plugin development: if you have off-topic functions you surprise users or overlap other solution. I hope more improvements that directly solve related problem would come up.