Yes seltzer water can and will hydrate you just like regular water will.
However you should still drink regular water for hydration because too much seltzer water can be bad for your kidneys and other health.
But research has shown that seltzer water is just as hydrating as regular water but you still do need to drink regular water that is not carbonated.
Seltzer water and other carbonated water can taste bitter to some people because of the equilibrium between dissolved CO2 and H2CO3 which is further in equilibrium with protons from its dissociation by virtue of it being a very weak acid.
Some people say that it tastes bitter when they drink carbonated water or other seltzer water and some people say it doesn't taste bitter.
To me I also notice that seltzer water tastes bitter but my mom says it doesn't taste bitter to her.
However we all enjoy different things and our taste buds are different.
Seltzer water is good for you in moderation even though it tastes bitter but you should avoid drinking too much seltzer water because it could be harmful to your health and cause bladder infections as well as kidney disease etc.