I played Samus a lot in both Brawl and Smash 4, and she seems to be better overall in Smash 4, but not with some nerfs. Though definitely not bottom tier.
In Brawl her only good kill move was her d-tilt, which is sightly nerfed in this game, but in exchange her f-smash, u-smash, Charge Shot and Screw Attack became viable KO options which is well worth the trade off. However her z-air is not as good as in Brawl, which I loved spamming back then :,(