I played for the full hour last night, and then during the afternoon one today, but not the morning one.
It was mostly fun, I like the goal of painting the area as it seems a bit more n00b-friendly than other shooters, since you can still score points without kills. It also seems like there will be some strategy to learn with those mechanics and the weapons and how everything comes together, but I didn't quite pick up on much yet in just an hour on two maps. I do think it has more depth than it appears, especially since during the second hour, people definitely played better and it was tough for me to win matches.
However, it seems people think the roller is the best weapon, as most everyone started using it. And it was tough to overcome teams with 3 or 4 rollers, as they can paint the ground very quickly and killing them doesn't accomplish much. In fact, we never won any games where the opposition had more rollers than we did. That said, the full game has more weapons, maps, and options, so hopefully there will be better counters to the roller, and some maps where it's not much good.
I thought the default controls were awful, so I switch to stick controls, but I don't really like dual-analogue either. I hope that they add Wiimote support at some point.
Definitely bummed about seeing 24 people playing this game and not being able to join their matches. That's a new record for "most people online playing the same software," which was of course held by SmUsh previously, and then Mario Kart VIII before that. So I can say I won't be interested in buying the game until August at the earliest.