Yeah, Connect does grow on one more and more the more they listen to it, which is strange, because it's supposed to be a throwaway pop song that does the exact opposite of that.
Connect is utterly brilliant, and I thought so from the moment I heard it. Gonna get a little "music"-y here, but I love the way the chord sequence rises into a crescendo in the chorus, the way the drums build at the end of the verses, the "stuttering" effect near the end of the chorus ("itsumo mat-te-te"), the swelling violins, the awesome solo after the first verse, and the fact that it's so distinctly "pop", yet feels so orchestral and natural. It has a perfect, bittersweet melody, too, and even though I don't understand the lyrics without checking a translation, the song sounds almost "hopeful", in a way - and the fact that it's so damned catchy...
If you weren't singing along with at least the "kujikenaaaaai" at the end of the show-length version, then you were probably skipping the intro. ;P
I can't fault it, personally. Luminous and Colorful are fantastic, too. Turned me into a massive ClariS fan, mere weeks before they broke up. :X
... Then I started watching Oreimo and, when I heard them singing the intro, was absolutely ecstatic. Anyway, I don't know whether or not I mentioned this here before, but
I'm actually a musician who specialises in eurobeat (see: weeaboo dance music) - and I'm currently putting together an English-language remix of Connect. If it's a success, I'll do more anime remixes, so when it's done, I won't hesitate to post it here.