Used to cover this one when I was in a prog rock band.
The Inner Mounting Flame was a seminal album for progressive jazz fusion, as it was a largely undeveloped genre at the time, although Bitches Brew was leading the way for the new style. However, can you really say that you've heard a violin wah solo before this point? Running other instruments through "guitar" effects was becoming somewhat of a trend at this point (again, see Miles Davis), but these guys did it in a way that was very fluid and natural. Combine that with the wide array of other sonic textures going on here and arrange them in a way that only Mahavishnu Orchestra can and you've got yourself a pretty unique piece of work.