I am not a fan of the auto-run genre, so take this with a grain of salt.
Firstly, auto-run tends to be more fun at higher speeds, even starting off. This one is very sedate compared to ones such as Canabalt, and while the difficulty remains, it makes the overall experience less exciting. The jump is smooth, but somehow feels awkward, especially when I land on the trailing edge of saws I thought I could jump past. There's also a bug where if you got a boost, and you double jump, he suddenly is slammed into the advancing spikes.
I'm not sure if the bug requires more than one condition - I replicated it twice but failed to replicate it a third