It depends on what your goal is...as a record shot it's perfectly acceptable, and for many people that is ok.
At that distance and in those lighting conditions, you already know that you aren't going to be getting any "great" shots of the bird, and really that applies whatever gear you are using, so if you are looking to get a better shot I would say there are four main things that would need to be addressed...the distance to the subject, the angle that the shot is taken from, the cluttered and distracting background and the poor light.
As Robert says, it's a perfectly clear shot of a Teal. Your set up is fine for the lighting I would imagine but distance wise, perhaps a bit far. I use a bridge camera nowadays, with a DSLR and long lens I was always striving for better pictures and ended up accepting I was never going to have the set-up I really wanted and downgraded to something more portable, even though I knew the pictures were only ever going to be 'ok'. I'm sure, however, if that Teal was half the distance away the picture would have been much nicer