I've been debating between buying it here or or Steam. I noticed that a game update went out two days ago in Steam, is it also available here?

Provided this version gets the same updates, I'd MUCH rather buy it here.

It's latest V15, also you can always update through patcher downloaded by version check before game start if there's any delay.

If you're considering steam and willing to pay full price anyway, you can buy the game directly from developer for 20$. You get drm-free download, a steam key AND Erlein's Handbook, a game guide containing detailed maps, a creature compendium, advice, secrets and riddle knowledge. Erlein's Handbook is, from what I've read, only available if you purchase directly from developer. You can also buy art book and/or game soundtrack for 5$ each. Again only buyable directly from dev.

Btw, GOG price (€18.19) is slightly cheaper than Steam (19,99€), for us Europeans at least. Dev price is currently cheapest converted to euro's (€18.0349969) but you may have to pay conversion cost depending on your bank.