I have a car which does only has a cassette player/FM radio. Originally I thought I'd buy an FM transmitter but I yet have to read a good (honest) feedback about them.
It's an oldtimer (convertible) so audio quality doesnt matter that much so i thought I'd opt for a cassette adapter.
have any of you made any experiances with either? RRS SC Bonatti Grey

Cassette adapter works fine in my case. I didn't go with the FM tuner because most of the comments I read back then were negative. 2009 Range Rover Sport 2.7 TDV6 SE, Alaska White, Almond leather, tinted windows, active rear diff, tow pack, HiICE, full spare: gone and already missed

2004 Fiat Panda 1.2 Climbing 4x4
http://www.youtube.com/watch?v=fAg4DdXAp7Y

Yep, go for the cassette adapter, far better sound quality than the FM transmitter.

I have bought and tried several FM transmitters and I have yet to find one that works well enough, mainly because its so hard to find a "blank" FM frequency. Gone - 2008 Stornoway Grey RRS 2.7 TDV6
Gone - 2009 Buckingham Blue RRS 2.7 TDV6
Gone - 2010 Alaska White RRS 5.0 V8 Aspirated
Gone - 2017 Chawton White RRS 5.0 V8 Supercharged
Current - 2010 Java Black RRS 5.0 V8 Aspirated
Current- 2024 RRS P400 SE Dynamic

Never had any problems with FM transmitters, but the cassette adapter seemed to have the better sound.

The only advantage for the FM transmitter - it`s a tidier option, no messy wires.