I used to love water weird's coolness, especially for my chambered reef/wandering whorl/flashflood deck, but as a fourth card in a difficult to execute combo, he doesnt do anything that a good scout cant do.
His attack and health are so paltry compared to Guuthlun, undead octopus, and alearwyn barque, that he's basically a space filler. Drawing two in an initial hand is really bad. And some boards have little to no water on them. In all my games using him, I can remmber one time where I was able to cloudburst an adjacent hex and kill a dimmed treeherd. Compared to all the times it's been killed by a ranged figure, or a wind mogi, or manganite, or KDPW, etc... and he seems essentially like an enchantment you can shoot at.
Now if he could exit the water, like any good snake, I'd be way higher on him. I'd even pay an extra flux.