Both great handhelds with different strengths:
Pros: Smaller/lighter, built-in memory (16GB, non-expandable), sleek slide design.
Cons: Limited non-expandable storage, no UMD drive (digital only), smaller screen (4.3"), pricier at launch.
Pros: Larger screen (4.8"), UMD drive for physical games, expandable storage (Memory Stick), cheaper (especially used).
Cons: Bulkier/heavier, older design, no built-in storage (needs Memory Stick).
Other factors: PSP 3000 has wider physical game selection; PSP Go cheaper now used; personal preference matters most.