Yes, they have many similarities to the surface of Mars. Obviously there are differences also, but first the similarities:

• Very dry due to the katabatic winds
• Cold, though not quite as cold as the coldest temperatures even at the Mars tropics.
• Moisture mainly found as thin films of brine (some of the proposed habitats on Mars are similar).

It’s one of the places on Earth so cold and dry that the life there consists mainly of microbes. Multicellular life can be found almost everywhere on Earth. The main exceptions are driest areas of the Atacama desert and the McMurdo dry valleys. But on Mars this would be one of the most habitable spots on the surface - for that reason even if Mars developed multicellular life, maybe even has it now deep below the surface somewhere, it seems unlikely to have much of it on the surface now except possibly lichens. Though of course it is risky to make such a generalization based on our DNA / RNA / Protein based life as the only biochemistry we know about in the universe so far.

Differences include

• Doesn’t have the near vacuum conditions of Mars and the CO2 only atmosphere, instead it is full atmospheric pressure and oxygen rich
• Doesn’t have anything like the same huge changes of temperature every day from day to night.
• Has long periods of darkness and long periods of light
• Doesn’t ever get quite so cold - Mars gets so cold that carbon dioxide freezes out temporarily as dry ice many nights of the year even in the tropics (this is what causes the frosts first photographed by Viking - a mixture of ice and dry ice). This happens occasionally in Antarctica mainly in high mountain areas but it’s rare.
• The salts are chlorides instead of the perchlorates and it doesn’t have the hydrogen peroxides of Mars. All the Martian salts have a tendency to be highly oxidized, chlorates, perchlorates etc (even though there is hardly any oxygen in the atmosphere).
• Doesn’t have the high levels of UV (though the higher mountains in Antarctica have amoungst the highest levels of UV on Earth along with extremely cold conditions)

McMurdo dry valleys in Antarctica

Researchers scout out field sites in Antarctica's Beacon Valley, one of the most Mars-like places on Earth. Image credit: NASA

These valleys lie on the edge of the Antarctic plateau. They are kept clear of ice and snow by fast katabatic winds that blow from the plateau down through the valleys. As a result they are amongst the coldest and driest areas in the world.

Katabatic winds

The central region of Beacon Valley is considered to be one of the best terrestrial analogues for the current conditions on Mars. There is snowdrift and limited melting around the edges and occasionally in the central region, but for the most part, moisture is only found as thin films of brine around permafrost structures. It has slightly alkaline salt rich soil.

Don Juan pond

This small pond in Antarctica, 100 meters by 300 meters, and 10 cm deep, is of great interest for studying the limits of habitability for present day life on Mars.

Research using a time lapse camera shows that it is partly fed by deliquescing salts revealing dark tracks that resemble the Recurrent Slope Lineae on Mars. The salts absorb water by deliquescence only, at times of high humidity, then flows down the slope as salty brines. These then mix with snow melt, which feeds the lake. The first part of this process may be related to the processes that form the RSLs on Mars.

It has an exceptionally low water activity of 0.3 to 0.6. Though microbes have been cultivated from it, they have not been shown to be able to reproduce in the salty conditions present in the lake, and it is possible that they only got there through being washed in by the rare occasions of snow melt feeding the lake. If this turns out to be the case, it may possibly be the only natural water body of any size without indigenous life on the Earth. For details, see #Lowest water activity level for life on Mars.

For more about this and other analogues of Mars on Earth see my Places on Mars to Look for Microbes, Lichens, … - Present Day Mars Analogue Habitats on Earth.