Alpha Protocol is a good RPG, most skills are useful and your actions have significant consequences for the plot, the latter being probably the biggest draw of the game.
However, the rest of the gameplay is nothing special, combat in particular is kinda bad and there's a lot of combat in this game. I don't recommend playing on the highest difficulty.
That being said, I still believe the game has value for people who enjoy spy stories and watching their choices play out.
Finally, the game can be a bit unstable so I recommend taking a look at the PCGamingWiki before trying it.