What does adding Koto change

I was looking through phrases on my denshi jisho and came across I don't like you

あなたのことは嫌いです

Does that have any extra meaning than simply saying....
あなたは嫌いです？

Also what about if I was to tell a girl I liked her using koto ha suki desu or somethng similar? Would it be any different from simlply suki desu?

I'd say "... no koto" makes it a bit more roundabout.

People might prefer to add it to say things like "I hate you." But with "I like you," if you want to be direct, you simply say "Anata ga suki desu" or "(insert name-san) ga suki desu." "Anata no koto ga suki desu" sounds like a somewhat shy person - so girls might use it more than guys :)