Yesterday's Enterprise

I watched this episode of Star Trek:TNG the other day and I have to say it is one of my favorite episodes for many reasons. It involves time travel,an alternate time line, and creative story telling that makes TNG so interesting.
The Enterprise-D scans a temporal rift just as the Enterprise-C travels through the rift. Once Enterprise-C is through the rift, everything changes on the Enterprise-D including the disappearance of Worf and Troi and the appearance of Tash Yar. As well, the bridge changes, the uniforms, and the mission of the Enterprise-D which finds itself at war with the Klingon Empire. I love that Guinan is the character that ties everything together with her special intuition. She realizes on an intuitive level that the Enterprise-D has changed dramatically as well as its mission. She cannot provide specific details only a general feeling. As the story progresses, Lt. Yar learns she is dead in the other timeline and requests to board the Enterprise-C to help in the return to the appropriate time. The 26 year time difference makes possible the subsequent capture and death of Lt. Yar by Romulans of which we learn in future episodes called Redemption I and II and Unification II.
We have once again, the idea that our actions of lack thereof can set into motion a series of events that could have easily gone in a different direction had we chosen differently. In this episode, the crew restores the past based on intuition, reason, and Guinan's trustworthy character. However, the past is not completely restored to the way it was because Lt. Yar traveled back in time 26 years.This did have a direct impact on the Enterprise as we see in future episodes.
Each time I watch an episode of TNG, I am so impressed at the story telling, how modern the episodes look even though they were made many years ago, and how great the acting is.