Hello there, nice to meet you!
I'm new to the Splatoon franchise. I don't have the Wii U so I never got the chance to enjoy the original Splatoon. But I did participate on Global Testfire for four rounds, one hour each. Based on the experience, the camera and control are the biggest challenges for me. I got used to it by a little bit by the 2nd and 3rd round, but still not enough since most of the players are so darn good and very fluid on splatting people around, I'm pretty sure none of them are newcomers.
For the camera, the motion control is a bit confusing at first. There's an option to turn it off, but relying on just one analog stick to handle the camera didn't works well for me. So, I ended up just having the motion control but with less sensibility.
For the control, I tried using handheld mode and tabletop mode (with and without grip). Handheld is my favourite, tabletop without Joy-Con grip second, and with grip the least. Holding the Joy-Cons separately is quite interesting way to play since it gives more freedom to both of your hands. Handheld mode is just great because of the motion control.
For the weapons, since this is my first Splatoon experience, I don't know if any of them are any different from the original Splatoon. Other than Splat Charger, all three weapons are pretty noob friendly, in my opinion. Splattershot's and Splat Roller's special are powerful. Splat Dualies have my favourite sub-weapon, I love the feel of throwing the Curling Bomb and then dive into the path it creates, priceless. Dualies' special, the Ink Jet, is great but it leaves you vulnerable in the air, easy prey for Splat Charger user. I rarely use Splat Charger for the global testfire, but definitely going to give it a try in the main game later.
There's one game where I face this amazing Splat Charger player that end up having 10-0 for the result, should've screenshotted it. He basically just stay on the bridge in the middle of the area, then splat every single players from my team easily. Even if we tried to get close to him, he just dive and immediately splat us as he pops up. Crazy player! I assume this is the uber tier that many original Splatoon players at. From what I read, the matchup of original Splatoon is pretty broken, so I hope I'm not going to meet them uber players very often lol.
Based on the short Global Testfire experience I had, I think the game is very fun to play, even for someone new to the series. Definitely going to pick the game as soon as it comes out! I hope I can meet any Splatoon player around here. Just, be easy on me.