I just bought the new Dragonforce and it's pretty good. The new singer is definitely one of the best imaginable replacements, but I don't think ZP will ever be truly replaceable. I don't really like that they cut all of the songs so short, because now the guitar solos aren't as long or interesting. A couple of the songs sound like they are straight off of Sonic Firestorm which is a good thing.
I think this is going to be a grower. It's definitely better than Ultra Beatdown, but not as good as the first three. Hopefully I'll have a review up soon.
8/29 - Borealis
9/6 - Gruesome
9/9 - Axxion, Amulet, Manacle
10/3 - Hibria