Samsung Galaxy s3 must be worst in all of the S series. Its predecessor S2 is a very good smartphone made by Samsung . Their smartphone to phablet conversion in S series starts from S3.
S3 may have sold in large quantities because of the establishment of new features during that era. But overall performance of the phone is rated bad.
Its main problem was the fast draining of the battery and overheating. Battery backup is one of the main aspects when a smartphone is concerned. Phone hanging was one of the major problem too.