Funny how everyone claim areas are 'rough' without living there.
I'm in Cranbourne East which ifs a couple of km's away. The main development Marriot Waters is far from rough. There's schooling on the site not sure of the quality - if its like ours its adequate but the parents tend to bitch and whine on facebook pages. Due to population growth schools are locking down catchment zones. For secondary schools the public ones with the best reputation are Elizabeth Murdoch in Langwarrin & Alkira (Cranbourne North / Narre Warren south) Primary schools seem to be much of a muchness.
Lyndhurst has easy access to city via train station Merinda park (they are currently upgrading the line so expect some bus replacements for part of the journey. Also the M1 (Monash) and the Eastlink (toll road) are in (relatively easy reach).
All in all an average to good area not fantastic. Reasonable ammenities and within easy reach of the city, Bayside beaches, Mornington Peninsula, Phillip Island and Dandenong Ranges.