In my reading today of The Cambridge History of Judaism, Volume Three: The Early Roman Period, I read about the Dead Sea Scrolls. I'll highlight two passages in today's reading.
The first passage is on page 814, in Jonathan Campbell's essay "The Qumran sectarian writings":
"[The view that the Essenes produced the Dead Sea Scrolls] gained widespread assent in the course of the 1960s and 70s, albeit with disagreements over innumerable points of detail. In the process, several rival theories contrary to the emerging consensus were thrown up for consideration, arguing variously that those responsible for the DSS were Pharisees, Sadducees, Zealots or early Christians or that the DSS had been brought from the library of the Jerusalem temple. However, such proposals failed to gain momentum, for the majority felt that the real but intermittent links connecting the sectarian DSS with these other Second Temple groupings paled into insignificance compared to the overwhelming case for an Essene identification. Not only had Pliny pinpointed am Essene site which must surely be Qumran. But clinching the argument were substantial agreements between 1QS and other sectarian compositions, on the one hand, and Philo and Josephus, on the other, across a range of features. Indeed, both bodies of material witness a deterministic outlook and hierarchical structure, avoidance of the Jerusalem Temple, an initiation procedure, communal property and food, and distinctive rules on ritual purity. Contradictions among the DSS, as well as between the DSS and the classical accounts, could be explained either by religious development over time or by the fact that Philo and Josephus were speaking in idealized yet imprecise terms as outsiders. Nevertheless, by the 1970s and 80s, some were expressing doubts about this Qumran-Essene synthesis. [They] argued that Essenism was a broader movement than that envisioned above and from it the Qumran group separated as a sect. Schism, not development through time, explains many of the differences between the manuscripts themselves and the contradictions they exhibit in relation to the classical writers."
The second passage is from page 852, which is from Daniel Falk's "Prayer in the Qumran texts":
"...a growing conviction among scholars that many of the Dead Sea Scrolls did not originate within the Qumran community---and many of the prayer texts fall into this category---raises the possibility that these prayers reflect Jewish practice more widely."
These passages are good "big picture" summaries of the state of Dead Sea Scrolls research, at least before 1999, when this book came out. Many appear to agree (with some exceptions) that the Qumran community that had the Dead Sea Scrolls was Essene, in some manner. But there is complexity to the issue. There are differences between elements of the Dead Sea Scrolls and how classical authors describe the Essenes, and there are also contradictions within the Dead Sea Scrolls themselves. Moreover, there is growing denial that the Qumran community even produced many of the Dead Sea Scrolls.
This is the big picture, but for specifics, a good source is Norman Golb's essay in this book, "The Dead Sea Scrolls and pre-Tannaitic Judaism". Among the issues that Golb addresses are contradictions in classical sources about whether or not the Essenes are celibate, contradictions within the Dead Sea Scrolls on whether there would be only one Messiah or two (kingly and priestly), and the solar calendar in the Dead Sea Scrolls, which is not mentioned by the classical authors (i.e., Pliny, Philo, Josephus).