Bruh...it 100% deserved all of it's negative reviews.
Unleashed is a game that forces the player to endure a drawn-out shallow beat 'em up game with a slow-moving clunky character, basic unimaginative platforming, banal puzzle design, and zero enemy variety all for the sole purpose of padding out the game. It tries desperately to be classic God of War but ends up feeling like a lesser version of that LEGO Star Wars from 2005. And lets not forget the incredibly repetitive battle music that blares over the unique tunes whenever you encounter a group of enemies...UGH!
It also further pads itself out with tedious medal hunting, where the player is forced to explore frivolous hub-worlds with either a clunky 3D Sonic that controls like ass at normal speed, or a big dumb warehog that moves like molasses no matter how fast you go.
The game also pulls another unnecessarily intrusive move by sometimes forcing the player to go all the way back to Spagonia to talk with Professor Pickle before they can start a new level. Like these aren't big cutscenes or anything, he just talks to you with text bubbles.
In addition to this the game forces the player participate in random 6 minute long flight levels featuring brain-dead QTE shooting mechanics that make Sonic Adventure's Tornado sub-game look like Star Fox 64. Its embarrassing.
And when the player FINALLY gets to the fun part, high-speed action platforming, its not uncommon for those sections to run at, like, 15fps. They also feature too many simplistic repetitive QTE segments, and really cheap deaths. They also have conveyance issues; Sonic goes so fast that the level assets often begin to blend together making it hard to know where one is going. An issue that ranges from kind of annoying because you've only been stopped by a random pillar or something, to downright frustrating because you've hit a wall over a deadly body of water.
And 10 YEARS after Adventure 1 the homing attack and light speed dash are still unacceptably unreliable, often careening players to their doom for no discernible reason.
I will never understand the "unfairly maligned classic" narrative that Sonic fans have given to it over the years. The best thing it ever did for the series was giving us Sonic Colors and Sonic Generations, that's it. Oh, yeah, and the music was dope but that's kind of a free space on the bingo card for Sonic.