This is a awesome example for a ecchi anime.
It has the usual non blood-related sibling-in this case, twins- competing for their younger brother,Keita's attention and love.
The great art and colours are as amazing as they're ever gonna be while the enjoyment was enhanced by its art work.
The sound could have been greater but it has all the cliche, cheesy and sexual feel to it at different parts throughout the 24 mins of each episode.
I am glad they did not follow completely through with the manga as I really hated the a$$hole teacher from chapter 20.
Overall, i rate it as a 9/10 for its great art work and i really love the characters especially Ako & Riko. They really work well together as twin sisters when they do ecchi stuff with Keita and also when they play their role as caring and loving sisters.
If you like ecchi, love-romance, harem and a slice of life type of anime then 'Kiss X sis' will likely be up your alley.