Yup, very good, far more better than only with analogs sticks, much faster and accurate aiming.

Gyroscopic aiming is the best thing to happen to console shooters... maybe ever. Its just so natural and intuitive. Its much more accurate than analog sticks and even the wiimote and nunchuck. Nintendo needs to add it to their next console.

It would provide an advantage, but since everyone would have the option to use it, it wouldn't be unfair.

Not gonna discuss gyro aim at all. I didn't like it. It's at least accurate though.
Standard dual analogue is not as good as with many other console shooters. Games like Halo feel way more accurate.
Local multiplayer, well Nintendo, check out games like Timesplitters, one and a half decades old. Should be possible to get 4 player split screen and bots as well. Shouldn't it?

That's cos Halo has heavy aim assist. ;)

Nope. You Can deactivate aim assist in most games. And they still feel more accurate. Aim assist in Halo usually depends on difficulty as well ans basically helps keeping an enemy locked on. Classic dual analogue in Splatoon just is not as good as in other fps/tps. Not so bad if you're rolling or have those SMG like 'guns'. Terrible if you want to go sniping.

Just going to flat out disagree with you there, didn't find it below average at all, my only problem was the inherent slugginess of dual analogue in general, which the gyro helped mitigate.

The problem with local multiplayer is that only one player would have the map, and thus he would be the only one who can make superjumps. Kinda destroys the balance.

You could probably however turn that feature off for local multi, then 2 vs 2 would be much better. Heck, you could even do console vs console 4 vs 4 that way

A free for all has the problem that it would need the same amount of bases as players and just as many colors, which would be very confusing and impractical for turf wars. Remember, it's not a standard shooter where the main goal is to shoot everybody, but to ink your turf in your color.

Having Bots would be a nice thing, but I don't know how big the hurdle for such an AI is, constantly switching beween coloring the ground and inking ennemies with non-too-perfect aim (no perfect play AI) sounds very complicated to do imo, so I guess while Nintendo might be able to pull that off, it's gonna take a while until the result is satisfactory.

I always check the names of the people you play against. The players dont change that much. They often remain the same for 6-8 games, with the odd drop out. That is my experience.

Did you play them already? I couldnt. Then again, I am only level 10 right now, so maybe later.