I hope they don't change the usual TF style, but at the same time if they change it a bit I'm also excited because it looks like they're working with really great composers for the songs, and they've got 4 really talented new members.
I'm guessing it's going to be an anime-opening-like high-energy and dramatic song for "worthless diamond" (the lyricist and one of the composers makes music for anime, the other composer worked with SMAP and Arashi!!)
I feel like yakusoku,renraku,kinenbi (promise/contact/anniversary) is going to be a very feminine/Tsubaki/pop sound, but high energy -- the lyricist for this song wrote a lot of recent UF hits like oyogenai mermaid, vitamin me/go waist/now now ningen, va-va-voom, lovepedia and teion yakedo. Hoshibe Sho tends to compose high energy songs.
and "namida no heroine koban geki" (sorry, I can't translate this one so well, something about a heroine of tears and drama) is probably going to be like...a sad power ballad based on the lyricist. the composers have worked with like...Arashi, AKB48, and Super Junior so ...high expectations for this one.
I am very very hyped for this single