Shadow's stages are easy and hard in a lot of cases. I call them the challenge mode version of each Act. Honestly this is where I feel the game is pushing me to play better.
White Acropolis: Destroying all the searchlights is completely different where as Silver and Sonic's version they were just there for added points.
Egg Cerberus: I finnally got the thing to throw Shadow off properly. Which you answer in return with a homing attack. Usually Shadow doesn't fall off unless you take too long.
Kingdom Valley: If you take the hovercraft section slowly you won't be smacked by a collapsing tower to your death. You can always abandon it as well for the other 2 hovercrafts later on if you're good enough. Rouge's section is simple since the keys aren't randomly placed everywhere (cough cough Adventure 2). You can also skip over into Silver/Sonic's Area of Kingdom Valley. I almost did for LOLs but decided not to.
Crisis City: You don't need to use the buggy. Heck its completely optional. I did find 1 Glitch with an invisible wall where I have to hold Right a bit in order to get past it. Other than that Its really the only glitch I've came across in this playthrough alone. Which supports my statement a few weeks ago about encountering very few glitches in a normal run.
Flame Core: Its easier to platform instead of running on the walls IMO. Its also a pain with Chaos Boost on since you might lose your homing attack but that's the trade off of Chaos Boost. But honestly don't die and its S Rank
Iblis Phase 2: Same as Sonic's except you can use Chaos Spear to light the orbs.
Tropical Jungle (Rouge): LMAO!!! HAHAHAHAHAHHA ARE YOU KIDDING ME!!! THE EASIEST STAGE IN THE GAME!!!! AHAHAHAHAHHAHAHHAHAH!!!!
Mephiles the Dark: I feel a little sad for the voice change on Omega but you can't always get what you want. He's still bad ass. Build up power for a Kaio....errrr Chaos Boost then let loose.
Radical Train: I personally think this is the hardest stage for Shadow. Vehicle required. Its the worst handling of all his vehicles. That motorcycle. It doesn't turn well. If you want to take the risk skip the first bike and use the 2nd one. But its risky. I know its probably stupid that Shadow can't catch up to a high speed train but a motorcycle can. Just deal with it besides, what would you attack the train with anyway if there's no to stop it in its tracks?
Silver the Hedgehog: A lot more room to move in. But has the same problem as Sonic which is getting away from Silver after attacking.
Aquatic Base: Rather easy since you don't have to do that walking on that metal bubble bit. Just don't get hit. Although that one hit I received as Silver made me LOL.
Town Mission #14: Protect mission.
Wave Ocean: Hovercraft is back. More stuff to fall on you. There's a section where its easy to get lost just look for a cave and hit the switch leave the cave and should be one over on your left.
Town Mission #15: Another Protect Mission
Dusty Desert: The last time we'll see the Hovercraft. Easy to get lost out here in this desert. Kinda reminds me of FF10's Bikanel Desert but not as long. Not fond of the platforming here. Well the pole vault part. I jump at the running sections to make sure I don't lose control. One thing I don't like about Omega is you have to be at specific range to use your homing shots. And here is where Omega's auto-targeting gets really confused.
Mephiles Phase 2: I'm not big on this boss fight. At least his minions look cool.
And now we make note that Shadow's been holding back this entire time. Bitch the glov......Bracelets are off. Now someone check the clock cause I believe its GO TIME!!! Then the appropriate song plays for the credits. "All Hail Shadow". Hardest story but IMO the best of the 3 stories. Honestly I have to say this is my best run of Shadow's story yet. LOL. I surprise myself sometimes.
On to the last story. Which is a pain in the butt. But definitely doable.