Did Titus get 3 or 4 weapons in space marine 1? I know Devastators had pistol+feet and 1 heavy weapon, Assault pistol+melee and Tacticals pistol+knife and a gun, but they could exchange a perk for another gun.
Melee weapons are kind of slow and even the mutant birdmen can block them. The cat and mouse of dark souls blocks and dodge breaks isn't good for the fast paced slaughter. But they... are usable, if a pale shade of their former glory. And no, the birdmen's shields don't degrade. They can take your beating ad infinitum. The block/parry would be fine against bosses, but on every enemy it gets too much real fast.
The bolt weapons, on the other hand, are absolute ass. The only usable ones are the Sniper variants, which come in instigator carbine, stalker bolter and bolt sniper form. The rest are just... just bad. Inaccurate and low damage. The heavy bolter is servicable but inaccurate. The rest are weak and innacurate save for the aforementioned sniper variants that can be useful for headshots with scope.
The pistols are generally weak, but ok for trash.
The Plasma gun is ok, but it does not deal good enough damage, and ironically doesn't really melt armour. It functions like a bolter should, if not usable for anything but close range.
The plasma cannon on the other hand is absolutely the worst ranged weapon. It has 30 shots worth of ammo, needs reload all the time, and all of its shots fall off to the ground really close to you. Aiming it is a bitch, enemy can dodge it, its ammo is miniscule and it is an absolute downgrade compared to the SM1 version.
The melta shots travel slower, and hit three times less hard. It also now needs reload. Did not try the multi melta. Likely gimped but the same.
The toned down Lascannon sniper is once again a call back to the failed game Eternal Crusade, as it takes a good second to charge for firing. It isn't as total ass as it was in Eternal Crusade, but it has like 12 shots, aiming is a chore, and it is a downgrade from the Bolter Sniper in all but damage/ammo output, which is the same. But you can fire the bolter sniper instantly, and fire it more, so if you miss its not that big of a deal. There is no reason to take it when you got a more versatile gun that can do the same.
Cawl's wargear choices are utter retardation. Guns that did not need reloading now do, and have less ammo and weaker shots.
Jetpack now takes an age to switch from flying up to going down, and the Tyranid snipers will snipe you out of the sky.
The game goes very annoyingly into the territory where melee enemies will stunlock you, and keep hitting you, and you die in 4 hits. Since there are often at least 3 warriors coming at you, this can result in instant death. So you either shoot them down or stunlock them, or they stunlock you. Its a quicktimed event, and either you win or they do, there is no recourse.
You can't even roll away and give them a faceful of melta, as by the time the melta shot hits them, they are on top of you already.
The Rubricae are better than the Warriors. They and the Gaunts are the most well designed from a gameplay perspective.
Rubricae can kick you really hard if you melee them, and teleport if you shoot them, but their attacks are easier to dodge and they aren't dogpiling you into stunlock. They can offer a consitent but not unfair challange. Provided you are not required to hold an objective where they can just snipe you to death.
The Gaunts are well done. The ranged ones scatter from you, and the melee ones try to dogpile and jump on you. This is fine until the melee warriors stunlock you or 2 venom cannon snipers or Zoants need you to roll around. But they behave as gaunts should, do a better challange than the Ork shootas who don't try to scatter.
Zoantropes are... they should be fine, in theory. But the inaccurate and weak nature of your ranged weapon makes them a chore, even though it is not the fault of the enemy design. They would have been a fun enemy in SM1, but here if you are melee, well, you are just dead.
Mind you in current year with luminaries like Concord, Dustborn, Star Wars Outlaws, the game stands out. Just as Baldur's Gate 3 before, it excels by just being okay by 2000s standards.
But it is definately a downgrade. If I were to be asked, I would give Space Marine a 9 or 10 out of 10, and Space Marine II a 7 or 8 out of 10. It is well done but the quality has dropped and it does not live up to its predecessor.