In love with Lightning... Rated 5 out of 5 stars
I fail to understand why so many users are having technical issues with Lightning. When tested in Thunderbird 17.0.6 on Windows 7 and Linux, it works great; no breakage, slowness, crashing, or anything.
I like the features Lightning gives me and its close integration with emails. If only Mozilla could fix the instability others seem to experience and merge it into Thunderbird for good. It would be amazing to have a calendar manager like this built-in by default. It would bring TB a step closer to the ranks of Outlook and Evolution!