While the actual comments vary widely, many if not most if not nearly all interviews conclude with somewhat similar comments, some sort of non-committal encouragement which really does not mean a whole lot.
Unless there are explicit cautions or concerns, overt suggestions that there are questions, the majority of interviewers tend to be a lot like the medical technician who is running a test, be that an ultrasound (other than a prenatal exam, in which the results are often happily shared during the exam) or other sort of scan, the technician carefully being neutral, carefully avoiding revelation about the outcome.
BUT that is most often GOOD news, by a big margin. The vast majority of qualified grant citizenship applicants sail easily through the various steps, including the interview, and thus it is usually the case that ALL is WELL. No problem. No reason to worry.
Unless, that is, the interviewer overtly expresses a concern, identifies a question to be determined.
Sure, it is not uncommon for applicants to walk away from the interview with erroneous perceptions, some walking away confident it went very well but then getting RQ later in the mail, others walking away disheartened and concerned because the interviewer seemed unfriendly or harshly judgmental but then soon getting the notice to attend the oath ceremony.
BUT MOSTLY, those who pass the test and otherwise know they are qualified, and who do NOT know of any reason why there might be some issue in their case, CAN RELAX and NOT WORRY. If there is a problem, almost everyone in that situation knows (even if they refuse to admit it) why there is potentially a problem.
The timeline from there can vary. The Decision Made and notice to attend the Oath may come soon, or not for weeks, or even for some months for more than a few. BUT if you have no reason to doubt the validity of your case, odds are very high that GOOD NEWS is on the way, sooner or in awhile.
