Very sweet of you to write a birthday song for your dad, that alone deserves 5 stars in my book, but it's about the song I have to review, so here we go.
To begin, I wouldn't tell if this is truly an Ambient since most ambient tracks are really spacy and it mostly sets up this relatively weird atmosphere. It sounds dreamy at first, but it suddenly takes a structure that could turn into a pop-music anytime.
The melody set is solid, very sweet, can't add much about it. Good use of the synth that goes in harmony with the bass and other sounds.
The kickdrum feels a little weak. I feel like you could've give it a little more power to it, so it leaves an bigger impact, but that's all subjective.
Overall I'd give this song a 3.5/5