This answer is a matter of opinion, and I am sure other people can offer
different viewpoints, but for myself, I would suggest focusing on
pygame1 for any projects you are starting *today* It has a long history
of being stable, people have made tons of games with it, and by the time
pygame2 is finished, it is very likely to have a backcompat interface so
pygame2 will be able to run pygame1 games with a minimum of
modification.
Maybe later, when pygame2 is a little more mature, it will make sense to
start with it, but your experience with pygame1 will certainly not be
wasted when that time comes.