When a psicrystal is destroyed the owner doesn't lose hit points nor does he have to wait 1 year to create another - although a strict reading of the rules would read that only 1 psycrystal ever per feat (i.e., there are no rules for replacing one).
A first level psion can "afford" a psicrystal, a 1st level wizard 99% of the time can not.
A psycrystal is a construct which has all kinds of built benefits like being immune to critical hits.
A psycrystal flies.
If the psion takes the psionic body feat he gets +2 HP for having the psionic affinity feat.
