There once was a show called Alias, and it was great. Created by J.J. Abrams, it starred Jennifer Garner as Sydney Bristow, a double-agent for the Central Intelligence Agency posing as an operative for SD-6, a worldwide criminal and espionage organization.
Then halfway through the second season, the series changes significantly. Some describe it as a reboot. I don't want to spoil it for you, but suffice it to say that you will know when this moment happens. It will feel like the story has come to a conclusion and a new story is beginning.
Stop right there. Do not begin the new story.
The new story is fine, but it is not special. It is frankly kind of ordinary. The show moves from an ingenious conceit to a standard plot that we have seen many times before.
I can't imagine why J.J. Abrams chose this path, but it was a mistake.
Here's the good news:
Alias ran for five seasons, piling up more than 100 episodes in the process. The first 35 episodes are outstanding and completely worth your time.
Go watch them.
If you want to watch the show, I've just reduced your commitment significantly and saved you the disappointment of the final three plus seasons.
Actually, in the spirit of full disclosure, I have yet to finish watching the final season. It was too weird and ridiculous and implausible to continue. In the spirit of completion, I may get to it someday, but I doubt it.
Time is far too valuable to waste on bad television.