It can be quite difficult. The enemies are tough and there are often a lot of them. You need to be really good at using cover and managing your ammo.
The difficulty of the last mission varies from player to player. If you've been upgrading your character's skills and are familiar with the game mechanics, it might not be too bad. But for some, the intense combat and multiple objectives can make it a real challenge. There are a lot of things going on at once, like dealing with different types of enemies while also trying to complete specific tasks within a time limit.