Been watching the show from series 1 and just finished season 3. I understand why they decided to drop everything and just make specials, but the specials themselves lose meaning if each episode turns out to be a special-like plot. I absolutely loved Conversation Street and that's where you get the best of their chemistry together. There was also some great episodes of the past three seasons; car reefs in Barbados, skiing in Telluride, environmental cars, muscle cars in Detroit, the Scottish ring road, building caravans, and two amazing specials of Colombia and Mongolia. I don't understand a lot of negativity towards the show, it was fine for the most part.
With that said and this might sound weird, but I think they had more resources at the BBC. It seems to me that Amazon doesn't really have the same calibre of executives/creative team. However, the type of humour they wanted to showcase always put BBC on the fence in terms of being PC and allowing more mature jokes at the same time. Amazon's unique streaming allows them to be more freely when it comes to making a stunt or joke at the level they want it, but I do admit other episodes just seem a bit bland, heavily edited, or very scripted at times. Maybe their age is finally catching up with them compared to seasons 6-15 of Top Gear (which was the golden era of any motoring show).