Not many info or discussion i found about this streaming platform here especially about the content, region, pricing, vpn, apps, video quality and etc.

At first I had doubt. Prime Video content thumbnail does not look interesting and not many people talk about the content on this platform. So i decided to give a shot by free trial several episode The Boys, Jack Ryan, Le Mans, 7500, and many more.

Now i continue with subscribing. Have you tried ? Any suggestion what should i watch next ?

Already tried many years back. Very little content at that time, so eventually unsubscribed coz not worth it at all unless want to watch Clarkson only.
Is the library size and quality comparable to Netflix now?

That's very disappointing. They have a huge library in the US but very little in Malaysia. They should go back to charging USD2.99 per month.

Library size very very small compare to netflix. Video quality i think prime video better. I subs for variety from netflix.
Yes luckily now no need vpn but of course library is limited compare to US. I keep switching watching netflix, hbo, prime video every 3 or 4 days.

I agree that prime's video quality is better compared to Netflix even last time.
The 4k HDR of the Grand Tour was simply amazing! I'm quite disappointed that their library is still so small in Malaysia. Netflix library in Malaysia is already so small compared to other markets, Amazon even much smaller 
Not worth it at all to pay USD6 for the same small content.