Not a bad start, but really its not doing much. Just a simple tile based scroller. Very jerky too. I'm going to guess you're updating your tiles a row at a time? It shows when anything else is happening other than the scrolling. With some optimizing, even simply drawing a single tile at a time per pixel scrolled you can get smoother results, even on a bog standard a500/a600. You can also skip rendering a tile when the area of graphics is blank, which with something like Mario can be upwards of 1/3rd of the time.
Check out final fight aga as a recent blitz example, or a brief bit of my half finished "Dragon's Lair AGA" port:
[ Show youtube player ]
By the way, Reality is a piece of crap
If you think its quality then we clearly have different ideas of the definition of the word "quality".
It screams, "look at me, I'm made with AMOS"