For functionality, absolutely, but the previous three were definitely miles above and beyond comparatively. A reasonable price tag for what you get. This is just otaku fandom bait.
Splatoon amiibo and to a lesser extent the Zelda amiibo (If you own both HW and TPHD) are the only amiibo that are arguably worth any money and I still don't think they are worth €15
€15 for the content of all three Splatoon amiibo combined would too much money already, but 15€ for a third of the full amiibo experience is outrageous but then again stilll miles better than the throwaway junk the other amiibo offer.
The sadness doesn't stop there.
Not only are amiibo extremely expensive (Not taking into account the scalpers even), Wii GAMES and through Nintendo Selects, 3DS and even WIIU GAMES are being sold for €20.
Full games are being sold for the price of the glorified DLC.
Not just any game, but Super Mario Galaxy, A Link Between Worlds, Tropical Freeze, Ocarina of Time and probably a lot of classics I'm forgetting are being sold for the same price as a figurine that unlocks something you can watch on motherinking Youtube for free.
Games with content you can spend a lot of time in, full experiences, games praised and that are the best in their genre.
For the same price as your waifu statue.
And it goes even further.
Retro games are sold at an even cheaper price.
I bet that you can get half of the Legend of Zelda series for the price of your Toon Link amiibo. (Currently €40 where I live)
That's a lot of hours you can spend sidequesting but instead people wanna buy an instant arrow refiller that anyone in their right mind would sell for less than €2
Wolf Link is the only one worth its price (Five euro statue, seven euro dungeon, two euro doggo in BoTW and one dollar 3-star weapons in HWLegends + things like costumes in other games), but only if you plan on getting BoTW along with TPHD (HW Legends if you like Midna)
This is what amiibo are made for.
The main game gives a good functionality already, but other games in the series give even more worthwhile functionality so the amiibo turns into a season's pass of everything extra in the series.
This would be fine with costumes and trivial stuff as well, but you'd need ten to fifteen costumes to make up for its price.
A reasonable price for those amiibo would be 5-7€/$
Five dollars for the statue itself and two dollars to zero dollars for the extra functionality they give.
I don't own any amiibo and I'm proud of that.