I have some first hand thoughts. I think overall the quality is significantly poorer on GPT4 with plugins and bing browsing enabled. If you disable those, I am able to get the same quality as before. The outputs are dramatically different. Would love to hear what everyone else sees when they try the same.
No, while I have no hard data, the experienced quality of the default GPT-4 model feels like it has gone down tremendously for me as well. Plugins and Bing browsing have so far for me almost never worked at all. I retry these just once a week but there always seem to be technical issues.
