My comments:
-Terrain was pretty good, not top-notch, but still above average.
-So. Much. Default. Stuff. Seriously, change some stuff on the heroes to make them more unique. Make new heroes from scratch. BTW - Force of Nature is totally useless - no trees. Also, make some JASS or at least triggered spells.
-Text was sloppy. Go through and proofread everything, or have somebody do it for you. You should have proper grammar and spelling for everything, it makes your work look more professional.
-Too easy. I could breeze through the whole thing - in fact, I did. I lost ONE hero the whole time - at Illidan.
-WAAAY too many magic-immune mobs at the beginning. Seriously, the first half was 80% Sunfury Elites who are immune to all spells, 'cept for Bladestorm and Starfall, of course. So I was forced to simply buff myself and let them autoattack. Longer battles != more fun. Unique, challenging battles = fun (IMO).
Overall, I'd also give it a 5/10, perhaps a 6/10. It's a good foundation, but needs a lot of work.