I never played FO3/Vegas nor Mass Effect.
Play New Vegas instead of this. It's a much better designed and written game.
This game really is incredibly dull. I played it for a while last year before quitting after some ship crashed on the big planet - maybe a third, or halfway in? I didn't quit because of something I disliked. I quit because I had no more interest to keep playing. I put it down one day with the intention to continue, but I never did.
I didn't care for the world. The idea that corporations own everything and everyone is an advertisement-spouting drone was funny at first, but it really gets old quickly. You can kill anyone you want and still beat the game, which is a great design. But you know another game that allows you to do that? Fallout: New Vegas, and that game isn't filled with retarded NPC's repeating the same joke over and over again. In New Vegas, NPC's offer an interesting view into an interesting world.
From what I remember, the combat mechanics are slightly better than New Vegas. For example, monsters run away when shot at if they can't reach you, to prevent cheesing. But it's still duller. I was fast enough to run past all melee monsters I met making them a joke, whereas in New Vegas you're outrun by monsters such as Deathclaws, Cazadores and Nightstalkers and as such they challenge low- to mid-level players.
And in New Vegas you have tons of different ammo types, making for interesting gameplay. You don't waste your six .45-70 Gov't rounds on a Radroach. In The Outer Worlds, there are only three ammo types meaning it's essentially universal ammo. You'll never find grenades for your grenade launcher, you'll find "Heavy Ammo" which is also used for your hunting rifle and revolver. It's ridiculous.
To make matters worse, you're showered in ammo and I had thousands of every ammo type from playing the game normally without grinding.
As for the weapons themselves, they are all leveled. So you find a tier 1 Hunting Rifle at the start of the game. Then in the next area you find a tier 2 Hunting Rifle, which is the same except it deals more damage. Wow!!!
In New Vegas, you can upgrade some weapons but only slightly. The Hunting Rifle is always gonna be the Hunting Rifle, it'll never deal 10 times the damage it once did. This makes weapons in New Vegas feel unique and worthwhile, while in The Outer Worlds you're left with an interchangable and dull %WEAPONNAME%.
In short, the game is very similar to most Marvel movies: Dull, mediocre and unfunny.