Yes the Guna milan score is very good with 27.5 out of 36 , you need minimum 18 for marriage, so gun milan is indeed good. You should do Grah milan and you can check if this marriage should be considered. Will it be happy marriage or end in marital problems.
Grah maitri score is less and that indicates that both will have very strong likes and dislikes. They both will be strong differences of opinions. Strong ego clashes will be there. The good thing about your matching is that there is no Gana dosha and Bhakoot dosha. Therefore I suggest you doing a grah milan and then proceed ahead.