I like the 109 a lot. It is a very versatile plane and just really cool to fly and is my ride of choice. But I have to go with the guy at the beginning of this thread about the guns leaving quite a bit to be desired. I know some people will tell you to improve your gunnery but that doesn't change the fact that the single stream of 20mm is inferior. It still leaves you disappointed even when you have improved your gunnery because the gun system on the 109 leaves too many planes still flying around where almost any other plane would have it dead.
The result is frustration after getting hit sprites all over your opponent and nothing happening to him. The reason nothing happened is because not as many 20mm's connected as you think they did. He should have been dead. Chalk this up to poor gunnery or whatever, fact is too many people have poor gunnery in this plane so I have to assume it's the plane and not them. A common denominator is a common denominator. But with a lot of practice you'll get it.
For dueling it's totally cool. More than enough ammo. But taking this thing into the war is not the best option if you're a lone wolf. If you'll notice, you don't see many 109's landing with 5+ kills. 5 kills is shooting absolutely lights out for most pilots in this offensively challenged plane shooting ability aside. You have to have the opportunities first, which are rare because everyone has to fly 1945 aircraft in the MA and you can't catch them unless you fly a late, late war 109K-4. But typically 109 fans like to fly the variants that had a legit production and combat record.