There is something special about open baffle speakers. They aren't for everyone, but if you are seriously interested in hifi, I suggest you experience them at least once.
Compared to conventional box speakers, the sound stage is bigger and creates a more realistic sense of spaciousness. The sound is more immsersive and the sweet spot much bigger. It's much less important to sit in dead centre of the room, and the sound is less inclined to appear as if coming from two speakers. In many cases the need for a centre speaker is completely eliminated. Many describe the imaging as less precise, but I've found it to be overall more realistic and engaging.
The main difference
The most significant difference lies in the way open baffle speakers interact with the room. At high frequencies an open baffle speaker with a single dome tweeter will be the same as a box speaker. Into the midrange a box speaker broadens it's dispersion and quickly radiates a lot of it's energy to the ceiling, floor and side walls, transitioning to omni directional behaviour often below 1kHz. There is generally very little control of the interaction with the room and as a result, it's common to try to fix this with room treatment. Again this tends to deaden the room and take some of the life out of the music.
An open baffle speaker has a more controlled interaction with the room. As you can see above, the polar response of the open baffle speaker has more control over the dispersion. To the sides there is a null - this means less side wall reflections, and less ceiling reflections. The only increase is in the radiation from the rear of the speaker in the midrange. However, if set up correctly, this can add to the ambience and enhance the sense of spatiousness. It's also possible to eliminate completely the first reflection from the front and rear walls, if certain placement guidelines are followed. More >
A more comprehensive discussion can be found at Linkwitz Lab >