[Spoiler: Since the ending is where the series fell short, there's no way to discuss what the creative team did wrong without revealing it. Skip to the last paragraph, if you don't want to find out.]
I enjoyed the writing up until the resolution, although it seemed like it had to be a coma the entire time as I guessed in my review of the first series, and the misdirection of Tyler being mad comes off forced upon reflection. However, by trying to end on a positive note, the creative team throws logic out the window and does a disservice to themselves and the viewer by blurring the series' mythology.
After turning his back on his friends while they are in trouble, Tyler comes out of his coma, although that doesn't discount the fact that he may have traveled back in time. Tyler finds his modern life unsatisfying, so he throws himself off a building, which allows him to return to 1973 and save his friends. While it's great to see the gang back together, there's no real explanation of what happened. How could he return to 1973 by killing himself, and why would he think that he could, if that were his plan, because that's not how he got there? Being in a coma and being dead isn't the same thing, yet now his imagination and the afterlife are the same thing? The creative team copped out to create a happy ending.
The set comes with bonus features of behind-the-scenes looks at episodes "3," "5," and "7;" a tour of the CID set; and Tufty's cameo. "The Return of Life on Mars" (45 min) and "The End of Life on Mars" (28 min) contains interviews with the cast and crew as they talk about proceeding with the second series as well as wrapping it up. Everyone seems content as the creators explain what and why they did what they did, but none of them take into account what little sense it makes.