So I've beaten the game and have about 40% of the challenges done. I'm also on the Pump Man and Chill Man leaderboards so you can watch my replays there.
I have to say that this round of weapons is better than I was expecting after they were first revealed. A lot of them have secondary uses like MM9. The Nitro wheel, if you hold it out against a wall, will pull you up the wall. I thought that was cool. Only one I haven't found any practical use for is Thunder Wool. Triple Blade and Water Shield are essential.
I think the levels are easier than MM9's but I had more trouble in the Wily sections than I did in MM9. Also found the first wily boss to be cool.