I had a chance to fly the Delta Shuttle from DCA-LGA last week. I'm sure plenty have taken this trip before, so I'll only post the highlights.
Both directions I was on the new aircraft type, which was a B737-800. They are configured as strictly economy class (like all shuttles) in a 3-3 configuration. All seats had laptop power ports, so I might finally break down and buy a laptop power adapter now that both shuttle companies (DL and US with A3xx) have power ports in all seats.
I flew the 11:30a and 5:30p flights. The meal service on both was a small chicken salad on lettuce, some pasta (rotini), and a small piece of chocolate. I like this as a snack. The last few times I flew US on the shuttle, they give you this pre-packaged "Le Petit Snack" which is just a few crackers and some cheese. I'm much more eager to fly DL now that they have better meal service.
On my outbound, I was running late (I arrived 10 mins prior to departure) so I used the ticket kiosk to purchase my ticket. It took less than 2 minutes to complete the purchase.
On the return, I went to a ticket agent and booked a youth fare ($90.75 walkup, age 24 and under), which isn't valid until 7:30p. Then they put me on standby for the 5:30p flight. I've never seen a shuttle flight totally full, so going standby isn't that risky. As expected, 5 mins before departure they called my name and I got on the 5:30p flight. Note to others who are 24 or under: US won't let you do the standby on youth fare during the rush period -- you can only do this on DL.