I'm a bit short on time, so I'll just try to be brief in my analysis, though for someone as prolific and important as Renoir that might be difficult. The amount of improvements he made to art, such as discovering, alongside Monet, that shadows take on the color properties of their surroundings rather than just the assumed black and brown varieties, were absolutely great; though it's not surprising that he made them, since he produced thousands of paintings in his lifetime. Also, I find it rather tragic that in his later life, after 1892, he developed rheumatoid arthritis, which within a short number of years deformed and crippled him to the point where he was wheelchair-bound. He was to paint in that unfortunate period, but needed an assistant to place the brush into his hand. The sweet Armful of Roses was painted in that miserable time.
Venice: The Doge's Palace
Armful of Roses
Irène Cahen d'Anvers
Banks of the Seine at Champrosay
Woman at the Piano