Yes, similar to an ESL, they are dipoles and you have the back wave to contend with. They are different in that the tweeter and midrange/woofer panels are separate and you usually need to adjust toe-in to provide the best image. You can place the tweeter outside or inside but I have usually preferred them with the tweeter inside and toed in to point at the main listening position (MLP). That is what Magnepan also recommends for the best time-alignment.
Depending upon your room, placement in the room, and treatment, they can be very persnickety with regards to placement. Be prepared to fiddle for a few days to find your favorite position. Small changes in toe-in can make big changes in their sound, and position from the wall behind them will also impact the sound. Again IME they sound best pulled out at least 3' from the wall behind them (the "front" wall from the listener) with the MLP at the apex of an equilateral triangle or a little closer to the speakers. You should hear the image "lock in" and become immersive as you get closer to the panels, but as usual can end up with a funky "hole in the middle" sound if you get too close.
Treating the wall behind the speakers (again, the front wall from the listener's perspective) can improve the imaging (reduces comb filter effects) at the cost of a loss of "space" in the sound.
They are less sensitive to side walls, as well as floor/ceiling bounce, than conventional speakers -- at least from the lower midrange and above, where the panel dimensions exceed the wavelength of the sound waves.
HTH - Don