I went to Spain as a teenager and saw Guernica in person. It was the first painting to ever really have an effect on me. It's stunning. A perfect example of how art can transmit a message between people across time and space, I just knew that I was feeling how Picasso wanted me to feel. If you have the chance to see this painting you should, no website can do it justice (although this is a very nice try).
I have been to a bunch of galleries and seeing a painting in person doesn't usually make a difference for me compared to seeing it in a book. Guernica is one of the few that did. Perhaps because it's massive compared to other well known paintings. So, I just want to say, I second your recommendation for seeing it in person.
One thing I have not seen discussed here is the fact that this painting was commissioned by the (Spanish) Republican government. Effectively, there is a degree of propaganda to the painting. No shade on the guy… my other favorite war crime painting is the executions of the third of may by Goya, and it was also a political commission.