While SSE2 is a double percision IEEE754 compliant SIMD unit, VFP isn't. Actually VFP isn't even a SIMD unit. VFP does vector ops by sequencing scalar ones.
Originally Posted by WillyThePimp
On the other hand, the NEON instruction set doesn't have double precision instructions and its single precision is not fully IEEE754 compliant. Other disadvantages of NEON that i can think of are a shared register file with VFP while SSE has it's own registers (XMM) and moving a value from a NEON/VFP register to an ARM register is very slow, causing a 20 cycle pipeline stall.
So VFP is nowhere near as fast as SSE2 and NEON has much more limited use compared to SSE2.