Maybe there's just not as much to say? Unlike season one, season three was already well-liked by a majority of fans. Unlike season two, the HD conversion wasn't bungled.
Personally, I haven't been talking much about it because I haven't been able to afford the set yet. Money is tight, and watching the series on Netflix is a much cheaper alternative for me, even if it isn't yet the HD version. But I will pick it up eventually -- everything I've read about season three has been great.