A stompingly good additional campaign.
Most of all what I found most impressive about the extra campaign are the twists and turns that are conveyed through the story/script, as you'd expect in a Dark Elf campaign. I found both to be the best of all 3 campaigns. Furthermore, the scenario scripting is of a better order and the AI seems to work better, if still in the limited fashion of its predecessor. Units for both races are fun to play, moreso that you never really feel in absolute control of your fate as gold rewards are cut down to more sensible levels, restricting the number of replacements, upgrades, items etc that can be purchased between missions.
Cutscenes at important points are just as good, if not better than in the original campaigns, though the tweaks to central characters/leader appearances do not occur in this one. Voice-overs are even a tad better than the original, if thats possible - with the Orc dialogue some of the funniest I'veard in a longz time!
There is one mission where the Orcs are trapped that really had me stumped - for a while. The final mission is exactly what the game deserved, with a v. difficult decision to make.
For what it is, Battle March is a very good add-on to the base product, if it doesnt quite add anything new to the mix. What it does add - new races, units, leaders. landscapes/maps and campaign, it does it with quality.
Really you should only get this if you liked the original game.