Um... I found the GC2 review that said it wasn't as good as part 1 a little vague. Could someone please elaborate?
Also, do either game have skirmish modes, or is it just scripted missions, single player?
GC 1 is little more 'tactic'; almost always you don't need to rush and can think about next moves. GC 2 is for sure faster, less time to think about tactics (but it's still important), quite simillar to World in Conflict. In GC 1 you have campaign, also there is possibility to playthrough missions from campaign seperate as single missions. GC 2 has campaign, single missions, skirmish, custom maps.
. GC 2 isn't worse from GC 1. It's just different. All depends from play style you like. For summary I advice anyway to start from buying GC 1. Story from game is awasome.