Hi PS Nice to see you here, again!The biggies:
His Mars conjunct your Moon/Mercury - very hot, he's probably very attracted to you but may come off as too aggressive or insensitive sometimes. Arguments are possible, be careful not to overreact.
His Saturn conjunct your Sun - strong link, very binding. He has the more responsible role here, and may appear cold or critical after some time. Try to keep it light and harmonious - communication is key, don't let rensement set in!
His Neptune square your Sun - potentially deceptive, he may lead you on or lie to you. Try your best to see him exactly for who he is and not what you'd like him to be. He can easily fool you and take advantage of you, so bear that in mind and work on your discerning skills. You can ask some trusted friends for their opinion on the situation, just to be sure.
Mercury trine Mercury - very good for communication, you can easily get each other.
His Sun/Moon square your Sun and square your Moon (by sign) - some basic ego clashed are possible, and it can feel as if you two are on different wavelengths emotionally. You're probably more outwardly sensitive and emotional than he is, and he can have a hard time understanding where you're coming from. Just accept your differences and focus on talking things out - you're both very Mercurial, so communication is key.
Hope this helps some!