Much Better...
... but keep going. Some cool "dark" atmospheric music might be fun. Perhaps a different one for each level. As far as making it more challenging, what if "death" drops the soul when bumping into something. The timer is maybe a little off... should perhaps go just a little faster, and/or get smaller timer boosts when droping off souls. As far as flavor goes, I think the levels are varied enough but maybe you could put different types of souls in the levels. Dantes "Inferno" had a different level in hell for the different offences. You could use that idea maybe to inspire different themes in the appearance of the level. Or use the idea to add another different kind of soul to each level. Just try to keep the clean look and its simple charm at the same time.