My personal opinion is that soy milk tastes like grass... I've tried it in coffee, alone, on cereal, but I just can't avoid feeling like someone dumped a handful of freshly cut grass in...
Almond is pretty good on it's own, but in coffee it tastes like marzipan... It's not bad, but not the taste I want in my coffee.
What funny soy milk are you drinking? It tastes distinct, for sure, rather than being sweetish like oat or almond milk. But in terms of viscosity soy milk has them beat.