It must have been an emotional rollercoaster for people involved with the Personal Genome Project this week. Monday saw all the excitement of a press conference and announcement of the data release, but by today at least one blogger says he's disappointed by the output. Daniel MacArthur at Genetic Future writes that "the data released so far makes for pretty desultory reading." He acknowledges that this is a preliminary version only and says he expects quality to improve considerably. But right now, he writes: Even making some generous assumptions about the quality of the sequence and the size of the targeted regions, the data files currently posted on the PGP website would have a per-base coverage of around 0.5 times - in other words, each base in the target regions has been sequenced less than once, on average. That's far too low to provide useful information about the patterns of variation in these regions.