Wolfenstein is a shooter that comes directly from the early 2000.
If you hope to see something similar to Battlefield or Call Of Duty, forget it. It feels like one of the first Medal Of Honor on PS1. You have a star in your compass at the top of your screen and it changes direction as you progress. There is plenty of missions, around 10 if you only complete the main missions. There are around 5 secondary missions. I recommend you to do them since this gives you money to upgrade your guns, and you will never have enough of it. That should take you a good 10 hours to complete the game. There is also plenty of guns and upgrades, starting with some machineguns going to the Tesla gun.
They added some abilities in this Wolfenstein, as being able to go through specific walls or ladders, use a magic shield, fire stronger bullets, etc... This adds a little something to the game, without being too much. For sure, you will have to use them under some circumstances, but most of the time, it will not be necessary for you to use them.
The AI is probably the worst that I have seen for a while. The enemies are so slow to shoot at you that you almost have the time to reload in front of them. You should be playing at least at difficult. However, if you do so, you may have some hard time against the bosses. They are simply at another step. You have to learn how to kill them, you will not be able to kill them by chance.
In the end, you will be able to enjoy this game if you loved old shooters, but you may find it obsolete if you are a fan of the new style shooters.