Hmmm, some controversy creeping in...
Xenon II was looked awesome in the static screenshots and for the first ten seconds I thought "Wow, this is the game I'm going to ble playing non-stop for the next six months!"
However, I have to agree that yes, the scrolling was a little jerky (as was Xenon and Chaos Engine, both Bitmap Bros games also) and that the repetitive music did grate after a while. The thing that bugged me most was that the game could be played entirely from memory. After sixteen years since I first played it, I still know where each baddie sprite is going to appear.
Shadow of the Beast was another case in point. The demo must have sold thousands of A500s thanks to it's beautiful graphics and stunning soundtrack. Underneath however was very little of substance, get close and you notice that all the sprites are limited to four colours and that foreground scrolling was a tad jerky. It was a classic case of being seduced by the graphics and sound.
Coincidentally, both games were the catalyst that inspired me to save my pennies and pester my parents for an A500. The less glamorous games of the time stood the test of time much better IMHO, as I still occasionally play Batman the Movie, Turrican and Battle Squadron.