Complex sentence: The all-metal monoplane Buffaloes that equipped these squadrons were an advance on the biplanes that Fisken was used to, as well as the Wirraways he'd flown during his fighter training, however, the stubby Buffalo has acquired a mixed reputation as a fighter.
Split into simpler sentences: The all-metal monoplane Buffaloes that equipped these squadrons were an advance on the biplanes that Fisken was used to, as well as the Wirraways he'd flown during his fighter training. However, the stubby Buffalo has acquired a mixed reputation as a fighter.