Ah, they all blow. IMO, if you advertise overnight, then overnight it should be. If you don't ship on holidays, you don't have an option to overnight the day before. If you don't ship on sundays, you don't have an option to overnight it on a saturday. I think what gets people pissed off is the rude awakening they get when they pay extra for overnight shipping and get 2-3 day shipping instead. AT the post office/shipping office you can at least catch this before it's shipped out - when you're ordering from an online retailer, 9 times out of 10 you get your shipping confirmation and find out there... then cannot cancel the order since it's been "processed already."
I had a girl at the post office pitch me their overnight shipping on a package - guaranteed 18 hours! I start filling out the paperwork and say "so it'll be there by tomorrow?" She then tells me no, their overnight guy had left for the day (an hour before their cutoff time), and, it wouldn't really get there till tuesday. Wuh? So, explain to me again why are you trying to sell me on something you don't actually have at the moment?
I ended up bailing out of there and getting to the city post office on time to catch their delivery guy, luckily, so it did get there on time, but there'd have been no way it would have happened from the office I started out in. I asked her, if it wasn't going to be overnight, why I wanted to pay extra and not just go two day. She says "because it's guaranteed" ... what, late?
^ this is from their website. Note the "most" part in there. I'm standing there reading this and the girl is like oh yeah and we can't deliver to that town on a sunday or a monday... (but they could do saturday - wtf, it's 8 hours away, are we that backwater that you only do delivery to some towns once a week?)
If you don't have it, don't advertise it. I don't care if I have to pay more to get it overnight, I don't care if I have to jump through three hoops and dance around in my underwear - if I want to get something sent THAT badly and that's what I have to do to get it done, fine - those are the rules but it gets done as advertised. But don't say you can, then "oops no I can't" as I'm handing a 20 over the counter.
My thinking, overall, is that there's no such thing as last minute shipping. It may happen once and a while, but it's always at the last minute you run into bullshit, so it's not worth bothering unless you're prepared to put up with the bs. Generally it's the retailer on the other end failing to be clear what their stipulations are vs. the actual shipping company, though...just as the USPS BS was the girl at the desk trying to sell me something she knew wasn't possible from her little corner of the postal world.
Amazon.com had a thing recently where they had a trial membership of their fabulous new shipping program - for 70$ a year you get "free" overnight/2 day shipping on your orders. They had a free trial of this for a while - I thought wth, why not give it a try? So I signed up and made an order, set it to 2 day. The items showed as in stock and immediately available, but it actually showed up a week later. The same has happened with their 9 day free shipping thing.
It reminds me of - the first two days of an expansion, masters drop like nuts, then they taper off and you get wood or legendary. Same thing - for a while Amazon was shipping before their "9 day" shipping date for their free shipping, then it tapered off. Netflix was going so fast that if we got a dvd in the mail before our mail went out, we'd have one the next day. After a few weeks of membership, that stopped.
They're not "breaking" any rules by any stretch, but it's deceptive regardless.
FedEX Blows my ass.
Guaranteed Overnight eh? FedEX can blow me, I want my new phone 
Next day delivery by noon or by 3:00 pm to many destinations. 
