can Tilapia replace salmon in recipes and taste good?
It depends on the recipe.

As Jefromi said, salmon does have a different flavor. Specifically it has flavor. Tilapia doesn't really have much flavor at all. 

More importantly, salmon has about three times as much fat as tilapia. Salmon holds together better than more fragile white fish. This makes grilling salmon much easier than other fish which fall apart.

If your recipe highlights the flavor of the fish, or relies on the fat or cohesion of salmon then you should not make the substitution.

On the other hand if your recipe calls for baking in a pan and uses other flavorings, such as lemon, that can overpower the flavor of the fish, it would be a good candidate for substitution.