Honestly, for a shotgun like weapon, I am a little disappointed in the kill power of this weapon. And the utility that the shield brings doesn't really seem like it is worth it. You can't really carry hard with this weapon, but at least the ink coverage isn't too shabby. This weapon is definitely meant to support others, but I feel that other weapons do that role much better.
As for the kit, I really think it is redundant to have both sprinkler and ink storm. Would have really liked to see something like splat bomb or any other offensive sub to give more options for the weapon's rather underwhelming offense.
Weapon is pretty good in turf wars; I was able to consistently get over 1000 points in it on a regular basis, and that is without the win bonus. Have yet to try out the weapon on ranked, but I think that splat zones is the only thing this weapon is going to be good at.
Overall, the Splatbrella is a fun weapon, and while it isn't terrible, it isn't great either.