This game is clearly MP orientated and should be bought and assessed with that in mind. If you are looking for a strong solo experience there are other shooters out there designed in this way like Killzone and such which would provide more of the experience you may be looking for. It's multiplayer that keeps you playing for weeks, months and even years not single player.
Lastly Bots are crap in every game ive ever played so what exactly is the issue for Brink?, that Splash Damage failed to revolutionize computer programming and take Artificial Intelligence to the next level?. Or maybe that the heavy use of objectives and multiple ways of completing them exposes just how little bot AI has actually advanced industry wide in the last 10 years.
In a game like CoD which is almost entirely deathmatch your bots dont need to do anything but shoot and move. The current standard of bot AI using the big advancements of the last decade like ducking in cover when shot at or moving between cover during no fire is adequate for the task but in no sense is it an achievement or progression.