Oh wow, I'm surprised at the negative reception this is getting. Just recently got a chance to use it and I've been adoring it. It's an odd weapon for sure, tons of bullet spread and terrible range means you really have to work for those kills, and the lack of a grenade don't help it's long range game. It's all about being quick on your feet and catching enemies off guard.
Similar to what Marraphy said above, it does heavily remind me of Team Fortress 2, not only the Spy class in general but also Scout's primary the Scattergun. It forces you to get up into the face of your enemies and promotes a run and gun style of play, though in Splatoon's case, splat an enemy and get out of there before someone with better range comes.
It's also insanely effectively at inking, the sheer rate of fire in such close quarters means it's perfect for quick inking, especially when it comes to making getaways. The tactic of inking and squidding in enemy territory to get out of harm's way is very easy to pull off here. Makes sense since this weapon seems to promote a more sneaky playstyle of getting behind and placing the beacons down for your team to use. Again, almost like you're playing Spy.
Of course I can completely understand how people can hate this weapon. It's not easy to use, if you go in there treating like the Aerospray or any other rapid firing weapon, you will get splatted a lot. Rollers are a nightmare to deal with here and trying to splat anyone head-on won't be easy. Also Killer Wail and Beacons aren't exactly popular choices for sub and special, coupled with how little people enjoy playing support, it's not going to be a big crowd pleaser.
Personally I could see this weapon being one of my all time favs, up there with the Dynamo Roller as a weapon not many are going to love, but it'll find a nice little niche fanbase that'll crop up when you least expect it.