In this poem, it seems that a speaker from South Africa has returned after some kind of prolonged absence, and he has found that nothing has changed: from the physical appearance of the place to the tensions and racism and economic disparity between whites and persons of color.
The tone, the way the author feels about the poem's subject, is sympathetic and even approving of the speaker. The speaker describes the "white only inn" where he sees the "crushed ice white glass, / linen falls, / the single rose." And though there is no sign that says only whites are welcome, "we know where we belong." In the end, the speaker feels like a "boy again"—as disempowered and angry as he must have when he was a child. He wishes he had "a stone, a bomb" to throw. His desire to be destructive is not condemned by the author; the speaker is presented as thoughtful and perceptive, and so his judgments feel accurate and understandable.
The speaker's feelings about the injustice he witnesses, feelings which take so little time to return to him, seem to indicate a theme: that racism and prejudice will only lead to violence. Perhaps, given the title and the emphasis placed on the fact that nothing has changed since the speaker was there the last time, another theme could be that social and economic and political change often takes a very long time and moves painfully slowly for those who lack power.
The visual imagery of the place for white people, with its "white glass," draped "linen," and the "single rose" on each table is contrasted with the imagery of the "working man's cafe." It sells food that you eat "at a plastic table's top," and you simply "wipe your fingers on your jeans" and "spit a little on the floor." These images, descriptions of things we can see with our mind's eye, really help us to envision the racial inequality in an obvious and tactile way. The author's tone toward the whites, we see from examples like these, is much more condemning and disapproving.