The Retina IIIc was a decent performer, although Leica has an edge in performance and much more robust construction. The main advantages of the LTM were compactness and a good variety of older lenses. I used them for 15 years before switching to the M series. For anyone wanting a pocket size camera capable of quality photos, the Retina and LTM are still logical. The slightly better versatility of the M made it a logical choice for me. The durability of one M4 for 42 years is testimony to Leica's engineering and build quality