This page tracks the many changes, upgrades and differences in the Nintendo Switch's Metroid Prime Remastered. Accordin to Nintendo's official documentation, the changes are as follows:

The first Metroid Prime game has been remastered for Nintendo Switch with HD visuals and enhanced sound! Explore Tallon IV from the perspective of Samus Aran. But beware: There’s more to this alien planet than meets the eye. When hostile creatures attack, fight back with Beams, Missiles, Bombs and more. In addition to remastered visuals, this version adds modern dual-stick controls, allowing you to move around while separately changing your point of view. It’s also the first time this classic game can be played on the go! The digital version of Metroid Prime Remastered launches in Nintendo eShop and in the My Nintendo Store on Nintendo.com … later today! The physical version of the game will be available in stores Feb. 22. [1]

Here's a comparison of the graphical chages:

Here are some other changes we've noticed while playing Metroid Prime Remastered.

You can now toggle on the narration not included in the US versions of Metroid Prime in the Pause Menu > Options > Sound. All narration is in English. Here are the options:

New control schemes have been added which can be toggled in Pause Menu > Options > Controls. These match both the original GameCube controller and the Wii Metroid Prime Trilogy release, along with new options.

There are additional control options including Swap Beam and Visor, Camera/Aim Sensitivity along Y and X axes, Lock On Free Aim can be toggled, and Spring Ball Senstivity can be adjusted.

Options including accessibility considerations have been added in the Pause Menu > Options > Display menu which now includes the following: