As noted in the essay that accompanied Loves of a Blonde oh so many years ago, the film is essentially divided into three acts. The first is a wacky mixer where awkward older soldiers mingle with shy and uninterested factory-bound women who have been shipped into a small town to balance out the gender ratio. The second is a more intimate look at one of the girls being seduced (or, really, prodded and cajoled) by a musician that played at the dance. The third and most appealing story is of the girl leaving the town to see the musician in Prague, where she ends up in an awkward situation with his parents.
All three of these stories have their charms, and Forman does two things extremely well throughout the film: merging plot and character motivation with social and political commentary quite naturally, and balancing on the line of quirky characters in over-the-top situations and authentic depictions of the realities of Czechoslovakia circa 1965. But its ultimately the humanity that shines through - both with the doomed couple (his awkward game is only matched by her naive pouting) and the boy's parents - certainly a stereotype by now but pulled off so well here that they seem like fresh and native characters in the film. The success of the depiction of both of these relationships is what makes the final sequence the best. It's funny and poignant in a very effortless way.
I've always had high esteem for Forman - he made a great film in each of the last three decades of the 20th century - and I enjoyed this film even more than Firemen's Ball. I think this is because of the almost neo-realist eye Forman trains on his characters. The film's plot and narrative style reminded me fondly of the Olmi duo of films Criterion released a few years after this, particularly I Fidanzati. Both of those movies feature big awkward dance parties, but the love story of the later film has many of the characteristics of the far less-romantic interactions here. Both films are very aware of the social situations which surround their characters, and these situations are not just used as a backdrop and/or metaphor for their characters actions, but are actually meant to have an impact on their behavior. Without the plant in Loves of a Blonde - not to mention the reason for the plant existing in the first place - the girl's decision to leave for Prague would make much less sense.
I bet this movie would improve with multiple viewings. At this point, this humanist and socially aware approach to the material is the most striking thing about the film.