It is challenging since the tech tree is often, if not always, a stunted version.  They also stick you into the map w/ 1 planet while your opponent may already have a dozen or so...

Then there is the fact that the typical "try to beat the AI into submission to win" may not always work.  If you're told to get X planet...just try to focus on completing that.  Total domination of the map before gaining the objective won't always be possible.  A few new strategies may come about by playing the campaign...

The story is ok, for those who like background.  There are some holes remaining unfilled at the end of the TA campaign, perhaps to be taken care of in GC3 though...

Definitly work from DL up thru them.  It would help with the TA storyline if you would, DL and DA kind of are their own seperate thing. TA brings it all together.

I first played the DL and DA campaigns once the TA one came out, I never actually thought about them until that point lol.