Wiktionary
a. 1 No more than adequate. 2 (context US idiomatic English) good - better than expected.
Usage examples of "halfway decent".
He was taken by surprise when he came upon one stretch of halfway decent road as his unit trudged north.
There was a very good view from this hill, and the only halfway decent stand of trees within half a mile was right where he sat his saddle.
The plan was to freak out the Dastard with her panties, so that the soul could catch him, and make him halfway decent.
If you're a halfway decent person, you don't go looking to kill people.
Too, Stephanie appeared to be involved with several community projects that had a halfway decent shot at success, and she was the only one in their group who could speak Spanish.
He'd have my head in a basket if there's even a halfway decent explanation.