Its an RTS... All you do is find,build,train,kill,win/die.
What did you expect, only people who are die hard RTS fans will like it.
As a general rule of thumb, RTS's for me are quite boring after a while.
Halo Wars is the exception. I could do the skirmish mode all day.
Halo wars is a lot simpler than a traditional RTS and it doesn't let you have complete control over things like base building and severely limits the number of units you can build. Hardcore RTS players hate that, but I like it because I don't want to spend hours working on a single mission like I used to do with Starcraft. But as far as being repetitive, all RTS's are repetitive, you just build a base, an army, and go send the enemy to hell. They can give you all kinds of objectives they want but in the end it all comes down to build, train and destroy.
and that's what i love in an RTS