Complex sentence: Eventually, in 1903, he was introduced to mainland-Greek literary circles through a favourable review by Xenopoulos, but with little recognition since his style was very different from the then-mainstream Greek poetry.
Split into simpler sentences: Eventually, in 1903, he was introduced to mainland-Greek literary circles through a favourable review by Xenopoulos. He received little recognition because his style differed markedly from the then-mainstream Greek poetry.