They're not exactly packing them in at the 1982 World's Fair, perhaps because the public already has perceived that the summer-long event is neither a brash extravaganza of gee-whiz entertainment nor an insightful exposition on the fair's theme, "Energy Turns the World."

Parking lots and hotels here were expected to be overflowing; already the lots are lowering prices in search of business, and hotels that thought they would be booked through October are telling callers that rooms are available.

For anyone curious enough to visit Knoxville this summer, here is a rather subjective appraisal of the five best and worst exhibits at the fair:

* United States. Although the $20 million federal pavilion is physically imposing and architecturally striking, it offers little toward a better understanding of energy-related issues. Still, the single most impressive experience at the fair may well be "Energy! Energy!," a film presented at a theater connected to the U.S. pavilion. Directed by Frances Thompson, who created the film "To Be Alive!" at the Johnson Wax exhibit at the 1964 New York World's Fair, "Energy! Energy!" cost the Commerce Department $1.25 million and fills a 65-foot-by-90-foot screen--the same size as the screen at the Smithsonian's National Air and Space Museum--with spectacular images of energy-consuming and -conserving processes around the nation, including several vertigo-inducing shots filmed from cars, trains and helicopters.

* Japan. There's a robot here who is a calligrapher, not to mention another spectacular film, with an extraordinary synthesizer soundtrack pumped through an extremely clean and powerful eight-way sound system. The film's topic is the conservation of energy in Japan, and it is shown on a semispherical screen as viewers watch from a moving platform.

* Control Data. This is the only exhibit that in any way attempts to explain how computers work, and it's done through a film. After leaving the theater, viewers can experiment with 10 computer terminals programmed for hundreds of tasks from tutoring Spanish to providing flight instruction.

* Federal Express. If the film presentation here is a bit hokey and quasi-religious, the pavilion compensates by using three computer-controlled lasers--green, red and blue--to paint nighttime clouds with designs and messages.

The Netherlands. Not an exhibit per se, but the Dutch corporation Vekoma has provided a 48-meter-high Ferris wheel that conjures images of the one at the Vienna amusement park in the movie "The Third Man."

* The Aluminum Industry. How about a vertical-axis wind turbine that uses rather than creates energy, driven by a motor rather than by the wind? Sound silly? Well, now you understand the 1982 World's Fair.

* Hungary. How about a six-foot wide Rubik's Cube that doesn't work, and a wall of mini-biographies that includes photographic homages to Hungarian composer Bela Bartok, Janos Irinyi, who is listed as inventor of the match, and others?

* China. The fair promoters promised a section of the Great Wall of China, and a restaurant staffed by chefs from Peking; they delivered 17 bricks from the wall and a restaurant run by a Chinese-American firm. The bricks are perhaps understandable; the food typical of the fair's fare: long on fast service and short of any real regional or international cooking.

* Italy. Hard for a guy whose last name ends in a vowel to admit this, but the Italians have managed to do here what they often manage to do at home: obfuscate and confuse appearance and reality. Much of the tribute is a tribute to nuclear scientist Enrico Fermi; the rest seems to have something to do with petroleum.

* Panama. The 20th of 22 countries to commit an exhibit to the fair, Panama was to have presented a model of its canal, but withdrew shortly before the fair opened. The pavilion stands empty.