There was so much sucking, in so many different aspects. They're sucking blood. The plot sucks. The romance sucks. You think you suck? At least you can watch this show and feel better knowing that it sucks more than you ever will.
So, since there's no plot, what is there? Oh yeah, romance. Kinda. Mainly them sexually harassing her, making her feel like shit, and then sucking her blood. They just, kept finding new ways to drink blood. Through the wrist, the neck, the chest, the leg. In a church, in her room, in the hallway, in the pool, in the bath. Poor Yui didn't have a moment of rest, and I honestly felt so bad for her. She was trying so hard to at least be a bit nice to them, but they were all such pieces of shit.
Subaru was nice though, he at least tried to help her out, although she was too stupid to actually take the opportunity. Ayato was a little angsty bitch, Kanato was psychotic and needs to stop, Shu is a lazy Tumblr boy, Reiji is a sadistic nerd, and Laito is a pedo/perv. They all have such different personalities, but honestly they were all horrible to Yui, who just got dumped there with no idea what the fuck is happening and why.
Yui's reactions to the situation were actually fairly accurate. I imagined what I would do in the situation, in the beginning at least, and I felt I'd probably do the same. See a guy with no pulse? CALL THE POLICE MY GOD. Strange people who are freaking you out? GET THE HELL OUT OF THERE. Someone calling you a Pancake? NOT EVEN WORTH MY TIME. Not escape when given the chance? AND THAT'S WHERE THINGS STARTED TO GO WRONG. At first it was kinda relatable but then Yui became the helpless heroine and I just pitied her at that point.
If you're interested in sexy vampire boys then this is for you, but if you want something beyond fanservice that has more substance, then you should look elsewhere. They have a Season Two, so you'll have a blast with all of that. Conclusion: It'll suck you if you let it.