Overall very nice double a single!
Ee ka > Ii yatsu definitely, but nonetheless they are both fantastic, catchy songs.
Tsunku's song chunking isn't done that badly, and is tolerable to a point where the songs are definitely growers to the least. I would say the songs are near perfect.
Make em awesome MVs and jackets and this single might have a chance to beat their record sales (maybe, not entirely sure on the numbers they have established thus far).