Wading River here...
The Miller Place/Rock Point area is great. I worked as a first responder for the FD in RP for a while. I wasn't aware of any 'bad' areas, just areas with smaller homes and maybe more blue collar incomes and maybe some vaguely red necky neighborhoods. There are some very densely packed neighborhoods with small cottage type homes especially in RP in the Terraces area. The schools are great. The district to the south mentioned above is Longwood. My neighbor taught there and it's not horrible and not your district. You want horrible go to Hempstead or Roosevelt. The police blotter reports are pretty benign but as with all of LI no area is immune to some notable crimes every so often.
The taxes are more notable in the Shoreham-Wading River SD and can sometimes border on ludicrous for the home. Brookhaven has high taxes like most other districts. If you're house hunting and are inclined on looking further east look into the Riverhead side of Wading River. A comparable home in Shoreham to mine would probably have taxes around 12 to 15k. My taxes are 10k with STAR and a town non combat vet credit(3200sf home with an in-ground pool on an acre.) The R'head school district doesn't have a good rep but its actually pretty good and getting better. SWR has a great rep there are actually some huge deficiencies that are only going to get worse over the years. There's no money for text books from 1st-5th grade, they get handouts, overcrowding, no program for gifted students and very heavy expenses for the administrators that eats up a good percentage of the budget.
Buying or renting?