I would absolutely LOVE to order a new P4. It simply looks amazing to me. Frankly, it makes the P3 look like a garage built prototype in comparison.
Sport mode, enhanced speed, longer flight times, improved gimbal, obstacle avoidance, touch flight, intelligent subject tracking, larger motors, better props... the list goes on and on. Plus, it looks so much more polished and refined than its predecessor.
Were it not for the fact that I've invested in a backpack case, 4 extra batteries, gimbal protectors, LED lights for the landing gear, carbon reinforced props, battery charging station, 100w power adapter, etc., for my less than 2 months old P3 Advanced (which is currently in warranty repair for an inexplicable ESC error), I would jump on this in a heartbeat. That said, the thought of having to re-buy all the 3rd party and DJI accessories just to be on par with where I am today is overwhelming -- not to mention extremely expensive.
For that reason alone, I think I'll sit this one out and wait until they release the P5.