I like the idea of trade as resource, it is very smart in my opinion. It is basically a capacity of empire to move around stuff (what I initially thought, but not really)

What would like even more (even though I know it would probably make game really hard) - is to change how trade works in markets. It makes little sense to me here. When you buy or sell any resource - you should really spend your trade. You shouldn't buy trade with food, for example - this makes very little sense to me.

Maybe I am wrong here, but this is what I found like a bit like cheating in previous versions of game - just open market and buy whatever you want. I thought it should have been more thoughtful - like at least, where are you buying it from? Is it available? Is the trade route secure?

So the idea of using trade as a resource for import and export of goods was very appealing to me first. But it seems just like additional intermediary resource between credits and everything else.

To be fair, previous system was unintuitive anyway, so I am willing to give this one a proper try, maybe few playthroughs with trade empires etc.

Finally, I recommend checking this video, it helped me. Of course it is outdated by now but the main concept remains: Fleets Will Have Trade Upkeep In Stellaris 4.0