This Blu-ray release of Star Trek: Season 1 is the best way to watch the original Star Trek if you haven't seen any episodes, ever. It's also great even if you have.
Here's what's new: they cleaned up the video so it looks nice in 1080p, and they added slightly improved special effects like the 3D models of planets when the Enterprise is in orbit. They might have made smaller touchups here and there, but you probably wouldn't notice unless you watched the "enhanced" and "original" versions back to back (both are included on each disc).
What they didn't—and couldn't—change was the goofiness of the original series. Not to get into actually critiquing the show, but it's very much a product of the '60s. It's dark, psychedelic and all the guest stars and red shirts are creepy beyond belief. But that's the point. It's Star Trek. You know what you're getting into, and this is the best way to watch the original series today. If you just caught the movie and want to see what the hell's going on in the original take, this is the way to go.
It is slightly expensive, at $65, but hardcore TOS fans will be old enough by now to spend that much on lunch.
When are they releasing TNG on Blu-ray? [Amazon]