There's at least one rest area southbound.
There's also a sign for a low bridge at 14'0" but it was a warning sign and I never saw the actual bridge.
Where it joins up with M14, there's a couple of sharper turns that are well marked, watch your lanes. South of M14 when you get into Ann Arbor area, traffic can get a bit heavy. Depending on the time of day, US23 can back up getting onto I-94.
Outside frankemuth, there's a quaint little strip mall that I will go out of my way to pick up Vodka and flavored vinegar's and oils. There's also Bonner's Christmas store too.