I had associated this in my head with Dick’s VALIS, which is one of his latest works (written 1978, published 1981, according to Wikipedia). I think just because of the similarity of names.
Ubik is in fact more of a mid-period novel (written 1966, published 1969), and it shows. Though according to the Wikipedia entry, ‘it was chosen by Time magazine as one of the 100 greatest novels since 1923.’ I find that a tad surprising, as it’s far from one of his better ones to my mind.
Certainly some of his tropes are there: strange warps to reality, confusion over who is and isn’t dead, that sort of thing. But it’s just not as compelling as, say, Flow My Tears, the Policeman Said, or A Scanner Darkly; nor as weird and fascinating as VALIS.
The characterisation is weak — which is probably true for most of Dick’s work, to be fair. But the story just doesn’t really get off the ground.