I don't mind that, because 40k Space Marines aren't really that different in terms of utility than a "regular" shooter character. As long as the gameplay is solid, then on the gameplay front it'll be fine.
To me it'll depend on faithful pace (and clunkiness), weapons, units, etc (in other words gameplay "feel" rather than graphics). That's really the main difference. It's not like 40k Marines are something totally different from a regular soldier besides a different flavor and strength of armor, weapons, though perhaps effectiveness of melee weapons. I mean they just got more powerful and flavorful assault rifles, SMGs, rocket launchers, HMGs,
I suppose the extra powerful armor and natural resistance lets them be less reliant on cover. But eh. They're really just very amped up soldiers, without much utility difference. Which is why they're a really boring (and novice friendly) army to play in tabletop.
Now if it were in a more open environment then Jumppack Marines would be a unique character compared to most shooters. And bikers. And Dreadnoughts. (Though other armies share those, too). Or I guess if they have Librarians and Techmarines or something.
That being said, the difference in flavor (mostly clunkiness and the feel of shooting rockets as the main projectile) does make a difference if you're a fanboy (which I am).
Setting-wise, in terms of being in a Space Hulk, it seems claustrophobic which is good. If it's not then it'll suck.
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There can be fun difference in gameplay, though. But that is more game-dependent than flavor dependent. The example would be Space Marine, where you have a mix of decently done melee and ranged combat, with the necessity to combine both, as well as very well done fluidity in switching between ranged and melee combat. And it's not typical hack & slash autotargeting ranged combat... It's shooter style with the necessity of aiming and choice of weapons.
But again that's more of an interesting gameplay mechanic than something that is 40k specific.
