The controls are fine, the graphics are among the best of the best, the level design is very good, the enemy AI is OK and your partner AI is quite good if you know how to exploit it.
Actually single player is very good if you know HOW the game is supposed to be played.
Sheva has two modes: Attack and Cover
When in Attack mode she"ll use the more powerful weapon in her inventory and actively engage the enemy on her own. When in Cover mode she'll cover you and use a less powerful weapon and will stay closer to you. You have to know which mode to put her in according to the situation and she'll provide very good help.
The same applies to Chris when you're playing as Sheva.
Read what I posted above.