Probably the most significant thing is that this is the last large body that we will ever see visited. The last 50 years in outer space exploration have been akin to the five hundred years of global exploration on this planet that ended around 1600. The planets (and former planets) have now all been visited. The travel time and technology needed exclude us from doing this for planetary bodies outside our solar system.
While it's still classified as a dwarf planet recent data has provided a more precise size of Pluto and it is once again the largest KBO known. A little larger than we thought (or at the upper range of estimates) and less dense that originally calculated.
CH4 ice confirmed at the poles and molecular nitrogen coming off the atmosphere at a much greater rate than expected.
I'm boycotting the next few days. I want to be knocked out when I see the imagery. This bit about it getting slightly clearer and clearer each day is losing the dramatic punch. I'll tune in on Friday to see all the amazing pics.
A week before the probe passed Pluto it went to it's secondary backup hardrive system and was successfully restored back to it's primary system 4 hours before the scheduled data pass at an 8000 mile altitude. Pluto has ice mountains 11,000 feet high with no meteor craters and is 4.5 billion years old and approximately 1500 miles in diameter.
The most amazing fact about is this mission is that after a 9 year flight spanning 4.67 BILLION miles, the little spacecraft missed its scheduled rendezvous time by about 70 seconds. That's 70 seconds out of ~9 years.
My cousin Rob stopped in for a visit and is sitting here right now telling me about his last project before he retired from Honeywell, which was that his team built and shipped the guidance system that's in New Horizons!!!