I stayed at this 1909 classic and was very impressed. I was abit cautious after reading many poor reviews, but this hotel did a great job and kept me quite happy. After an overnight flight from Dallas, I didn't have to wait and was given a room key upon arrival at 9am. The room was very nice and the bathroom was supplied with nice amenties. Beware of the strong water pressure. Night-time turn-down service is provided. The hotel has a nicely equipped health club including a sauna, whirlpool and locker room to freshen up after checking out at 12noon. This is a real extra bonus when your flight to N. America doesn't depart until late evening. You can leave your suitcases at the hotel while spending your last afternoon exploring the city. The hotel's location is close to the subway (I think it was the "C" line) and is a short walk to Calle Florida. You can pay with credit card or good old greenbacks.

Unlike some other reviewers, we had a perfectly good experience of this hotel. Very courteous and efficient staff; clean, well-kept and fair-sized room with good facilities; good check-in and check-out. It also has about the best location you could wish for in Bs As (at least as far as I'm concerned).
Down side? Yep, it's little down at heel in one or two places (look at the carpet from the foyer up to the lifts - slightly tatty, but hell, who cares?) but this is a hotel built years and years ago. If you want something that only exists as of now, go elsewhere. But if you want a very comfortable, well staffed and superbly located hotel, this must be hard to beat. (One big plus for us was that we hardly felt we were in a hotel belonging to a big chain.)
Good value too.

Good location and good concierges,especially Juan.These are about the only things good about this hotel
The bad was reservations efficiency.When we checked in we were told that even though we had printed Marriott reservation confirmations that, that meant nothing to the Marriott Plaza front desk because "we have our own system and we are not really a Marriott hotel,,,we still consider ourselves The Plaza,Buenos Aires"....WHAT ????
The bad included room service that despite 6 phone calls during our ten day stay only once appeared at our door with our order.That one successful call to room service resulted in two extra wine glasses to be delivered so that we could serve 2 friends wine in our room...For this "priviledge" the Plaza charged us a non-refundable "rental" of $2USD each to "use" the extra glasses...How classy !!!!!
The bad also includes rooms that are small,unexciting and their age is obvious.
The ugly was the front desk check in service.For over an hour we were forced to deal with an abrasive,obnoxious and totally inefficient woman by the name of Lucila.During our one hour check in with this woman she came up with 5 differing dates for our departure despite having all of our Marriott printed confirmations in front of her.After coming up with these 5 differing results from her computer she told us every time that we had to move out on the newly found date because they were full...It was obvious that she was computer illiterate.We subsequently overheard other people attempting to check into this hotel shrieking at this same Lucila over her attitude and inefficiency.This is a woman who definitely should not have contact with the public.My suggestion to the Marriott is to re-train their front desk personnel and to send Lucila to "Charm School."
The one major plus to our Marriott Plaza experience was that the problems caused by the front desk necessitated us moving to the Caesar Park hotel for 2 days.Now that is a classy hotel.Great location,fantastic staff,wonderful rooms..in short everything the Marriott doesn,t have...My obvious recommendation...stay at the Caesar Park and avoid the Marriott.

My wife and I stayed two nights at the Marriott Plaza the week prior to Easter. Although I had booked a senior rate, the room was upgraded to a suite. We had requested an early check-in, but had to wait an hour until the room was ready, so maybe that was the reason for the upgrade. The suite consisted of an entry, bedroom, living area and bath. The room was handsomely decorated, in immaculate condition and completely modernized. The conceige handled our requests for a tango show and estancia visit, the business center had three computers and most of the first floors were wi-fi. We ate a light lunch at the grill next to the pool and breakfast buffet in the main restaurant, both good. The desk also scheduled a 5:30 a.m. taxi. The Plaza is on the main shopping street, Calle Florida. A couple of blocks from the hotel is the Gallerias, a world-class shopping mall.

Based on some of the recommendations from this site, my expectations were not high. Fortunately, my research proved correct and this was a quality hotel with comprehensive services and a efficient/friendly staff.