Comparisons to MTV Unplugged tend to be thrown around in an attempt to promote any pre-Unplugged acoustic music by linking it with a successful, more contemporary phenomenon, but Tesla's Five Man Acoustical Jam was actually a legitimate predecessor of the trend -- it bears a strong resemblance to early Unplugged sessions in its informality and sense that the band is just having fun.
Perhaps more importantly, the fact that a cover of the Five Man Electrical Band's "Signs" became a Top Ten hit demonstrated that acoustic rock & roll -- not just ballads like Guns N' Roses' "Patience" or Extreme's "More Than Words" -- could find acceptance and commercial viability with rock audiences.
As for the musical results, Tesla's originals generally translate well to the acoustic format, though some of the jams tend to ramble and lose focus, a fact underscored by the tightly melodic covers of '60s classics like "Lodi" and "Mother's Little Helper." Still, this adds to the informal atmosphere, and the album is a nice change of pace from the rest of Tesla's catalog.