So yes, I watched all the three movies before making any judgement. I only did it because I saw some comments on the movie (Them) saying that it was messy and then someone saying that it was best to watch the three to better understand. I started with Him, followed to Her version and ended with Them for chronological reasons. Some people say that Her is a better version, but I decided to stick to time factor and follow the directors way.
So is it worth it? *Really trying not to say any spoilers so I don't ruin it for you* Him really gets the guy perspective of everything that is happening around and we see only his version of events, his feelings everything about him. By now we don't really know what's happening and it seems just like a story about a break up.
With Her we get the girls version and here is were we really comprehend the trigger point. I love how they explore differences between the moments that we seem them together. I think it's pretty amazing because every time we put two people talking about things from their past, even though they lived it together, each of them always seems to have differences in their memories, so it's quite amazing to see it (a first time for me) in a movie.
Them it's the putting together of these two people. I confess I was a bit disappointed with this last version. I expected a little more after the first two movies and certainly a putting together of the pieces. Even though it still manage to surprise us with small differences of what we already seen. I guess after the first two I got my expectations high, but maybe it was too much. I tried watching it as I hadn't seen the other two and it was surprising how, even it seemed confusing at the beginning without seeing Him and/or Her, in the middle we get to understand things without they being showed to us.
The end was not absolutely what I was expecting. Here too I was expecting more. But somehow it managed to still conquer me. I guess on this part the soundtrack really gives an amazing help.
So yes, it's worth watching the three otherwise there are some little pieces that connect us to the story that you will lose. My advice: watch Him and Her and later watch Them. The soundtrack connects very well with the dynamic of the movie. This is a "dramance" and it's about love and lost so you can't expect much action or fairy tale ending. It's real life pouring on! Jessica Chastain and James Mcavoy perform it very well and what we have here is original cinema. Hope I've been helpful without spoiling.