Read them in my teens so the memories are hazy, but Brighton Rock is OK – sadistic cat lick street urchin running amok with his razor. Actually, it’s probably really tame by today’s standards. Heart Of The Matter is heavy on Catholicism, corruption and human failings. Ministry of Fear is a decent WW2 spy thriller with some unusual memory loss sequences, IIRC? (apt). I’ve also read The End Of The Affair but can’t remember a thing about it, except I thought it was the worst.
He’s OK but I never really got hooked on him. Greene and Muriel Spark (who I prefer) were converts, and converts usually tend to view Catholicism as being a lot more profound and intellectually complex than we born RCs do. Maybe it’s an ego thing; if you’ve made a conscious decision to emotionally and spiritually invest in the one true faith, rather than having it shoved down your throat from birth, you’re probably less likely to take the piss out of chain-smoking priests getting babies’ names wrong during baptisms / telling you you’re going to Hell if you read the Sunday Sport, etc.
Maybe I just read the worst ones. Surprised Burroughs liked him, to be honest - can maybe see a bit of him in Ballard, but it wouldn't be much more than 'a bit'.