You might need to think about drainage. Where does rainwater currently drain? Work it into your design. I like the look of your idea, though.

What is a step up patio? i much prefer deck to patios and on a slope much easier to build too.

I think it could be charming, a hidden garden effect with the proper planning. I could see a low rock wall as you have shown with planting beds in front to tie the two levels. The most important part will be the prep of the base for the patio. If you don’t have a stable base, ie: compacted soil, gravel, and whatever else is under the patio paving stones, the patio will fail. I would get professional help for the required base and the installation of the paving and the stone walls. Certainly, a deck would be much cheaper, but, we don’t know your budget or your neighborhood. Why don’t you get pricing both ways? When I look at two different ways to solve a problem, I price it both ways. When we were building our house, I asked the contractor if we could make a change. He told me it would be expensive, so I let it go. I spent 17 years wondering why I didn’t ask how expensive. I will never know if expensive was $1500 or $15000. Now, I always ask!

Aesthetically the rock works as I have 60' long 5' tall rock wall to the left of the steps going up to my stone fenced in vegetable garden. I had a price about a deck but expensive plus under the deck it would just harbor animals since I live near woods chipmunks, field mice, garden snakes my wife and kids would go crazy lol. The wall will be cement tacked for drainage and the patio drainage will pitch towards the back into pachasandra.