Evil Ryu has a mixture of traits from Ryu and Akuma, some things he has an advantage of over the other characters, but loses something.
His absolute things are:
Big damage
Great Focus Attack
Great Dash,
Good Walkspeed.
Great ultras, U2 is likely the best 500+ damage ultra in the game.
He builds meter faster than anyone in the game from what I’ve seen.
Some long ranged pokes and he forces stand in several of his combos.
He also has less height restriction on his (normal) dive kick.
Really good and powerful shoryuken
neat kara-throws and kara cancels
Some things he gets from other characters:
Good fireball with good recovery,
3 hit fireball,
Teleport (but not great)
He also has an ex fireball that doesn’t knock down but lets him combo into full animation.
Disadvantages are his:
low health,
slower normals,
difficulty opening up characters
lousy teleport
Basically he does the damage but loses some of the tools and normals that make Ryu and Akuma great. So you’ll have to play a bit differently.
He is fun to play and can rack up the damage and stun, but his tournament viability is questionable. Some think mid tier or lower, and some think he’s higher tier. There is still much to learn about him though.