If you have the patience to endure its hit-and-miss first act, the Rep’s sure-to-be-popular season-closer It Ain’t Nothin’ But the Blues (which has already been extended beyond its original 5/1 close date) will reward you.

This Tony®-nominated musical revue purports to be a crash-course in the history of the authentically American art form known as the Blues, but don’t go expecting to actually learn anything. Do expect a rousing, soul-stirring good time, with some incredible vocal performances and a decent sampling of the musical form.

The song-studded show features traditional African chants, Southern gospel, Delta and Chicago Blues, and even some hillbilly and honky-tonk music. Two large screens on the stage flash archival images from the appropriate time and place, and oh how I was wishing for a bit more info — timeframe, decade, anything — to help put it all into context.

But, again, education this ain’t. There’s a wealth of vocal talent on display, though. Most notable:

• Eloise Laws, hilariously ribald with “Someone Else Is Steppin’ In” and profoundly, crazily heartbroken with Nina Simone’s “I Put a Spell on You”. (Try to catch a non-matinee performance before 5/4; Ms. Laws won’t be performing every show, and she’s definitely worth seeing.)
• Jewel Tomkins, pictured above, tears it plumb up on just about everything she performs, especially the gospel number “I Know I’ve Been Changed” and the ever-haunting Billie Holiday classic “Strange Fruit”.
• Kingsley Leggs, a randy “Hoochie Coochie Man” who later laments when “The Thrill Is Gone”.
• Chic Street Man (don’t ask me what the hell that name means), makes for an enchanting “Rag Man” and a just-plain-nasty “Sidewinder”. (A very white audience member near me hissed “Disgusting!” at the highly-suggestive delivery of one particular lyric in the latter. Hee hee!)

Dozens of tunes, many of them amazing, especially after this gifted musical gang moves from the church house to the juke joint.