I've lived in Roselle over 10 years and for the most part I like it.
W. 3rd Ave is a decent area in Roselle and it's close to many stores, and the Post Office and public transportation. The main problem with Roselle is the high taxes. I think that's why so many houses are for sale in Roselle.
In my opinion the worst areas in Roselle are E. 10th Ave, E. 9th Ave, and E 11th Ave by St George Ave. There's lots of illegal activity in that area, shootings, drug dealers and gangs.
Good luck looking for a home. There are many beautiful houses in Roselle.