The OLED display on the original Vita is fantastic, but that's essentially its sole selling point. The LCD Vita ditches the glossy (fingerprint magnet) finish for soft-touch plastic, a more comfortable grip, better battery life (ranging from 2-4 hours more, in my experience), and trades out the proprietary charging cable for micro USB.
I wouldn't say trade your old Vita out, especially if it's still in working order, but as someone who's owned both, the LCD model is my favorite of the two. Plus, it's bright blue! That's way better than the stark black finish.