I was 5 yo at the time. The movie swept me off my feet and SW mania ensued. I recall my friends and other grade school kids talking about:

how many times they saw the movie

who their favorite character was

what was their favorite vehicle/ship

how many toy action figures/space ships they have

the new SW disco song on the radio all the time

which SW character they were to dress up as during halloween

kids wearing assorted SW t-shirts

I also recall many playground discussions about what Vader looks like under his helmet and whether or not stormtroopers were robots or humans and what they looked like without the armor.

I had a great Christmas in 77'. My parents got me the entire basic wave of action figs, the x-wing, landspeeder. My friends had tons of SW toys and it was great to get together and combine them all for some huge space battles!