Well, around here Amazon Prime orders are delivered by UPS, I've never had a lost package or had one delivered at odd hours or had boxes left in the rain.... Deliveries are the same way after I got Prime as before.
Sounds like Prime's delivery service depends on area. I requested Amazon ship via UPS, but they claimed they had no way to do that. I reported the troubles with the substandard, non-UPS delivery service employed for Prime in my area, but except for credits for lost packages, that resulted in no improvement. I ended up cancelling Prime. I'd probably have kept the streaming if that could be had without the problematic Prime shipping, but Amazon refused to unbundle the two.