So I had to have it. I loved my original PS Vita and I had to upgrade to the slim. It has 1GB storage, better battery life, is thinner, lighter, has wider grips on the back, but the screen is worse but honestly I couldn't tell. I think it is a good upgrade. I gave my old Vita to my brother. I really appreciate the new battery life. I played a few sessions and hardly noticed a drop in batteries. Awesome.
I recommend the Vita. I really like mine. It works even better as a PS4 accessory since you can stream your PS4 on it. Pretty soon it will have PS Now which will allow you to stream PS3 games to it. It is awesome. Get one.