Just wanted to report on my experience with PLUNA. A few days before my flight I got an email reminding me to check in online and save the charge for one piece of checked luggage, which I did. Had a small problem as it seems my name got reversed in the system (probably due to my lack of Spanish speaking acumen) but in the end I figured this out and used the online in both directions (though couldn't find a printer at my hotel -- Holiday Inn Montevideo -- so ended up emailing the downloaded return boarding pass to a friend back home who then faxed it to the hotel!
I was directed to their preferred check-in line at both airports having done the online thing. However, if you do this, print out at least two copies of the boarding pass as they take the one with the country exit tax at the gate as you board. (At both airports it was onto a bus to be driven a few hundred meters!)
Flights were smooth and fast/on time. The Bombardier 900s are new and in great condition. COmfortable seating in the usual 2x2 configuration. Storage bins were large for an RJ. Pluna does charge for drinks of all sorts and had a few snacks, but for such a short flight I passed on getting anything.
An aside or two:
At MVD I was paged and called back to check-in from airside as Pluna does not allow laptops to be packed in checked luggage, even when locked. Guess the theft potential is too great. Anyhow, it was handled cordially and I was able to go landside and get back airside with no problem.
There is no "club" lounge open most hours at MVD even though the airport does have one and it can be used by Priority Pass members. The Pluna lounge is now closed.
All in all, quite satisfied, particularly as noted the fare was well under half what other carriers were charging.