Never seen anything of George A Romero's films and never will - my brother saw Night of the Living Dead when it was shown at his university - he hadn't realised what it was like and it upset him more than any other film he had seen.
I certainly can't argue that Romero's oeuvre can be a difficult watch for many ("intense" and "realistic" are descriptions you hear a lot), but he is unquestionably an important figure in horror cinema. I think I would summarize his contribution as:
1) He essentially created the modern zombie movie (although I believe he never actually used that term himself);
2) He pioneered a documentary-style approach to horror;
3) He also helped develop the horror movie as social-political satire (his early zombie movies were satires on consumerism) .
If you don't fancy his zombie movies, you might want to consider "Martin" - a reinvention of the vampire movie, decades before that became an overused clichÃĐ. Although not typical of Romero's work, it's regarded by many fans as being amongst his best (Mark Gatiss singled it out in his documentary series "A History of Horror", and as you've probably guessed, it's one of my favourite horror movies).
"Martin" also inspired one of the oddest musical tributes in movie history:
RIP, George.