Ritsu Onodera. He's our resident uke. Basically once upon a time he goes to school, and falls in love with his sempai. He confesses to his sempai, then there's some implied sex. Sorry, you don't really get to see anything. Then, a few years later, Ritsu is hired as... get ready... a shojo manga editor. Of course there's a little wtf moment, and he meets the rest of the editing team, which happens to be entirely male. There he meets Masamune Takano, his high school (or university.. it's not clear) sweetheart.
Well, I must say that the plot is pretty similar to Junjou Romantica, but I have a confession to make. I hate JR. Mainly because Usami and the other couples pissed me off. Even though SiH has a fairly similar set up with the obvious uke/seme (bottom/top) thing going on, I like the idea that we're avoiding rape. It's nice to have a yaoi where the spark that lights the fire isn't rape. You'd be surprised how common a theme that is. I thought it was quite funny how Ritsu's previous job was working with Usami from Junjou. I laughed a little too loud during his flashback. But it's nice to see that the creators have a sense of humour.
SiH was actually pretty tame, yaoi wise. The only thing you really get yaoi wise is some flashback kissing, and a rather hilarious sexual harassment kiss. Yes. Sexual harassment. It's work... right? I mean, what ever pays the bills, and makes that shojo manga epicly romantic. Basically, for the first episode, I'm going to call it shounen-ai, not really yaoi because yaoi=sex. I loved the way that the creators played off of the yaoi and shojo stereotypes. It's quite ironic when Ritsu's commenting on why "everything is all sparkly" during a kiss scene in the shojo manga. The creators seemed to have a lot of fun. What was also pretty funny was the whole 'cycle' with the editors. It's like their own little menstrual cycle... except with shojo manga and less blood. Overall the humour was quite clever and despite Sekai Ichi Hatsukoi's primary demographic, I think everyone will have at least something to enjoy. I just really appreciated the fun tone of this anime, and the little quips, references, and forth-wall poking.
The animation was good. Usually yaoi and shounen-ai anime have awful animation budgets and everything is just... uck... *cough*TogainuNoChi*cough* but the animation was pretty smooth. I still have a bone to pick (heh) with the art style in SiH. It's the same as Junjou Romantica, and I really wasn't a fan of it. THE PROPORTIONS. But at least the humour and the story makes up for the disproportionate lips.
Oh... and on an unrelated note: Katsuyuki Konishi voices Takano. If that name means nothing to you, he's the same guy that voices Kamina in Gurren Lagann, Laxus Dreyar in Fairy Tail, Demon Eyes Kyo, and Ash's Snorlax in Pokemon. Never gunna look at them the same way... are you? I was also really happy to know he was Kiriwar in Togainu No Chi. <3
I actually recommend everyone to give the first episode a try. It's quite cute, and quite funny. No sex, and overall tame for a yaoi. I can't vouch for later episodes, though. Anyways, give it a watch, and let me know what you think below. :D
Takashichea did a summary here. Read it if you're a bit scared to watch the anime. :P