Here's what Eric Brown had to say about the 109G that he tested:
"Longevity of service has never characterised the fighter. Indeed, until the last decade or so it was possible to count the years in the firstline lifespan of the average fighter aircraft on the fingers of one hand. Tending to prove the rule have been the few noteworthy exceptions to be found in the annals of fighter development, perhaps the most outstanding of these being Professor Willy Messerchmitt's Bf 109. There was, in fact, nothing mysterious about the Bf 109. It was simply a well-conceived, soundly designed fighter that maintained during maturity the success that attended its infancy. The blind flying panel appeared somewhat better equipped than that of the contemporary FW 190. The auxiliary services were mostly electrical apart from the undercarriage and radiator, which were hydraulically operated, and the flaps which were directly connected to a manually-operated handwheel and in consequence, tediously slow to lower. At its rather disappointing low-level cruising speed of 240 mph (386 km/h) the Gustav was certainly delightful to fly. This was then Gustav. By the time the evolution of Willy Messerchmitt's basic design had reached the G-series, it was no longer a great fighter, but it was still a sound all-rounder and the Bf 109G had greater flexibility from some aspects than preceding sub-types."
Hardly a damning or biased conclusion.
