Anon who actually played the remake here
I'm here to give an unbiased review
The game is honestly an upgrade from SS in every Quality of Life situation.The addition of the circles to highlight action commands, the sped up travel time, the Fast Forward button, as well as small menu stuff like the guide options are all QoL changes that make the remake better both in gameplay and in aesthetic/graphics.
The only two critiques I have for this game is some tracks of the remake sound worse than the original, but from actually playing the game, these amound to 3 tracks total: Cackletta's final theme, Cackletta's theme, and one more in an area that sounded meh.
The rest are perfectly fine in-game and are either an upgrade (bean bean town, tehee valley) or sound equally fine.
The second critique for this game is the fact that they used the koopa troopa spritework from past games with this engine and did not respect the style of the SS Koopeas (they looked goofier in SS). Besides the koopeas as well as some other enemies which they used Koopa Troopa and goomba spritework, the aesthetic is a general upgrade.
The game was really fun and it was a good excuse to replay SS.
I enjoyed the new minigames and the ability to farm beans if you feel like min-maxing like an autist. Bowser's Minions is also a solid sub-story with 5+ hours of content to have fun with. I enjoyed the backstory and plot stuff revealed on it
Oh, I guess they removed the posters from the yoshi cinema that were references to other nintendo games, they replaced them with prior Mario & luigi games character cameos instead (Bowsers inside story block guy and the characters from dream team). That's whatever, personally. What was a bummer was that they removed the character appearances at the StarB cafe, but they did keep the items which make reference to other games.
Overall I'd recommend it if you like the mario & luigi games and wish to replay or haven't played SS. You can totally play SS for the first time with the remake and you won't really be missing much besides sprite changes and some references. The game also has the GBA tracks if you wish to listen to those, so you're covered on what's important on not to miss.
Mario & Luigi / Mario RPG thread