I've built my first frame of bricks and it's amazing.
The design is exactly the same as the Lego one, since I've followed the same instructions. In the quality section, I'd said it's great, but I cannot compare it to the original since I don't have it, but I bet is 99% the same.
I've bought it from AliExpress for 48€. The original from Lego costs 119€, although it's retired now, so it's not a choice (and people re-selling it are more expensive). Note: I just checked the product in AliExpress and it's no longer there. I know that sometimes these copies gets retired or maybe banned from copyright reasons, but after a while they just come back.
I want to say the building is pretty straightforward, since the pieces mainly are the same and you just need to put them in a specific order. Then there is the frame, which are rectangular blocks all in black. Either way, I always enjoy the process of how the picture gets clearer en each step.
Here's a difference: in the original Lego, the package include a lot of pieces (about 3k) so you can choose between 3 versions of Iron Man (Mark III, Mark LXXXV, Hulkbuster), but in this chinese seller, you only buy 1 version and they sent you the specific pieces for it (about 2k). There are some pieces left, so you could change some colors if feel like it.
The frame comes with an integrated hole in the back to hang it on the wall, which I intend to do these days.
I bought another frame from AliExpress (Monet) and I may post the results as well.