Shadow the hedgehog had an nice concept. The ability to choose your path and the gunplay were clever ideas, but it still feel flat.
While the ability to choose your path sounds good, the missions you had to do that weren't the normal routes were long and tedious. The lack of a radar system didn't help either. The gunplay was decent enough, but some weapons didn't lock on to enemies so you were force to manually aim at the enemies with floaty and slippery controls.
The environments were also bland and sometimes even reused. However, one thing I will disagree on is that how people think the music is bad. There were plenty of great tunes like Lava shelter, Cosmic Fall, and the main theme.
Making Shadow dark wasn't the problem...sure it was kinda silly, but it could've actually worked if they actually put more time into each feature.
If there were better controls, shorter missions, a radar system, better controlled weapons, better environments, and more diverse bosses, this could've actually been a great game. Maybe not amazing, but still great.