I attended two pre-release events on Saturday as they were run back to back. In the first session I won 2 and lost 1 and in the second I won all three.
In the first tournament all of my matches were pretty balanced and 2 of them went down to the wire, a high risk move that didn't work out caused me to have my only loss of the day. I noticed that there are quite a few moves in this set that causes splash damage which I like as it means you have to be even more tactical about how you play around that, also on the other side of it, it means you can win multiple prize cards with one attack.
In the second tournament I was fortunate enough to pull 2 Tapu Koko Gx's from my 4 booster packs (pulled 3 in total for the day!) meaning that I had a very powerful deck for the second tournament and didn't have any issues seeing off my opponents with one of the games being over within a few minutes. However I believe that is just luck of the draw, if you are fortunate to pull a Basic GX at any pre-release you are going to find things a lot easier as you will mostly go up against basic pokemon and decks that have very few trainers.
Overall it was a great day and I am really looking forward to this new set!