Sasameki Koto was sort of a mixed bag for me. When it was trying to be serious, it was pretty good (nothing spectacular, but fairly enjoyable), and some of the light humor was good, but sometimes it tried to get really goofy, and the humor it jumped into then just didn't work for me. That's an entirely personal thing though, I know there's plenty of people that would find that stuff hilarious, it just wasn't my cup of tea.
The animation was fairly average: nothing impressive, but clean and consistent. The characters didn't really have a lot of depth, they each had a specific personality type to portray, and they pretty well stuck to it. Not the most common cookie-cutter personalities, but I definitely got the sense of "I'm here to present the [personality type] character." Now, it was decently executed, so it didn't give a really cardboard-cutout feeling with the characters, they just could have been developed more. If it was longer, maybe more would have happened to develop the characters--it did have a completely open ending, so there was certainly room for it.
All in all, it was pretty average: glad I watched it, but I don't think I'd watch it a second time.