I think, very grateful. If someone is pointing out your mistakes and helping you, you must be grateful. Well, it is my opinion. 

Grateful, because I can improve my English.

i feel really honored when someone takes out his/her time and effort to correct my posts.

I feel happy. 

Grateful. My English is too good to ask for corrections specifically, but I know I'm still making mistakes. It would be great to have them corrected on the go.