"El Loco" is a solid collection of blooze-n-boogie from the bearded ones (and the less bearded Frank Beard), opening with one of ZZ Top's best songs, the superbly groovy "Tube Snake Boogie".
"I Wanna Drive You Home" and "Ten Foot Pole" are fine, bluesy, mid-tempo funk, followed by one of ZZ Top's very few real ballads, the nice, melodious "Leila", and the somewhat generic "Don't Tease Me" (it's not bad, it just sounds like a hundred other blues-rock numbers).
"It's So Hard" is a good slow tune, not really a ballad and not really a slow blues, but somewhere in between. And the double-entendre "Pearl Necklace" is one of the album's best rockers (and was one of the three singles lifted off "El Loco", along with "Tube Snake Boogie" and "Leila").
The album loses momentum towards the end, though, winding down with the somewhat forgettable, synth-heavy "Groovy Little Hippie Pad", the decidedly odd "Heaven, Hell or Houston" and the rockabilly-esque "Party On The Patio".
"El Loco" is not conistent enough to be a great album, but there are several excellent songs here, good enough for about 3½ stars.