I really liked the premise and the start of this book. I thought it was well paced, very entertaining and addressed some important social issues (prejudice, class consciousness, slavery). The writing was very good for the first 1/3-1/2, but then it got sloppy. I felt like after Matt met El Patron, things moved too quickly, the writing was much more expository rather than mysterious, and everything just got too convenient for me.
When Matt attempts to escape just before El Patron dies, it was unbelievable and too convenient for Tam Lin and Maria to be in such perfect communication (and know about the passages). Once he does manage to escape (again it seemed awfully convenient) his life with the Keepers was equally unbelievable. I get that Farmer is trying to say something about corruption and power and communism here, but really it was just too much.
I was also unsure as to why Celia and Tam Lin became so attached to Matt. He is the 9th of a series of clones; there have been 8 other boys in the past 100 years (obviously Celia and Tam Lin haven't been around for all of them), but why weren't they attached to any of the others? What makes Matt so special that he is worth risking everything to save? Further, why is Mr. Alacran so surprised to see Matt in the house (the day he hurts his foot) and why is he so put out? There have been 8 previous clones who lived in the Big House and were educated...this is not the first time? For that matter, why was Matt in the house in the poppy fields? Why wouldn't he be kept in the house from the beginning? Certainly I understand wanting to hide him from the kids, but the other adults would have seen at least 1 if not a couple of the previous versions?
Overall I think the concept was neat and the set up was great, but in the development Farmer took some short cuts and did not deliver.