The attack animations for spear are quite similar to the javelin in Diablo 2. I don't see those a problem at all.

For the 'can't hit things below me' problem, it's actually true for many other melee weapons. Spears are a bit even worse for small enemies like necks, surtlings and leeches, but they can be dealt with by the throwing attack. I can one shot leeches with a thrown fang spear.

On the other hand, I found spears very good at killing drakes. Just hide behind some obstacles and use jump attack to poke them after they fly close. The jump attack trick is much easier to do for spear than other melee weapons.

Throwing attacks can one shot drakes too, but I don't recommend that unless you fight on a very flat ground, or you'll risk wasting hours looking for your spear which slid down the mountain :(

For summary, spear is a very versatile weapon. Throwing attack gives you more combat strategies than all other weapons. Even Odin's weapon Gungnir is a spear.