This very, very big Reason article on Star Trek's greatness might be the best article on Star Trek I've read.

If you still believe Shatner is just a laughable ham, nothing will convince you otherwise. People of refinement know better and recognize Captain Kirk's total commitment, his vein-popping intensity, his refusal to be cooler than the material, as the acting equivalent of the right stuff--an indefinable quality, not quite stagy, not quite cinematic, at once too big for TV and just right for it. On a fresh viewing, it's striking to see how ably Shatner, Nimoy, and the late DeForest Kelley sell Star Trek. Because even if you never believe those tinfoil props are really phasers or communicators, you never doubt for a second that they believe it.