1) It's a nice school for young adults of average intelligence (meaning people who did "average" in high school) from Long Island. This is primarily the student population that the school attracts.
2) The school is more affordable than others. Most of the students get at least a little bit of scholarship money. Most students also save money by living at home and working part time.
3) Overall the quality of education is pretty good. Like all schools, the school has its good and bad professors, caring and uncaring professors.
1) Almost all of the students live within commuting distance and are happy with their lives on Long Island. So while the student population is nice enough, people are not really looking to make friends.
2) Because Adelphi's reputation does not extend beyond Long Island, most students seek jobs on Long Island. But there are very few jobs on Long Island and the few that there are pay very little. This a problem considering the high cost of living on Long Island. The professors and administration seek to "solve" this problem by pushing everyone to go to graduate school.
I wouldn't say that this school is "good" or "bad." Just be aware of what you're hoping to get out of a college and make sure that this school suits your needs.