First drone was a P4 this Christmas.
Two months later I have the P4, a Parrot Mambo, Eachine H10WD, Hubsan H107D+, and a Hubsan 502S. Yeah, I went a bit crazy
Hands-down my favorite indoor drone is the Mambo ($100), and it's not even close. It flies just like the P4, as it has visual positioning, ultrasonic ranging for AGL hovering, and a barometer for altitude hold above the ultrasonic range.
Hovers ROCK SOLID in place indoors, holds altitude perfectly. The controls operate the same as the P4, (that is, centering the sticks causes the AC to brake and stop in place).
The VPS is just a single, cheap fixed-focus camera pointing downward, and this is not a $1000 machine, so you CAN fool the VPS (move your hand under it), and pattern-less surfaces have position hold issues. This is no different than the P4, however.
The stability and positioning accuracy if this drone is so good that I have absolutely no issue at all maneuvering it over within inches of my head/face, then just let it hover there. No control input.
Flying the Mambo indoors will hone your LOS flying skills with your P4. You will have to spend another $30 and buy the "Flypad" -- traditional 2-stick controller. Out of the box you fly it with a smartphone app, which totally sucks.
Now, all that said. my second favorite indoor drone is the Eachine H10WD. This is a nano, about 2" across arm to arm. It has a barometer for altitude hold, and a 0.3MP camera for FPV flight! It is a blast to fly around the house, but without any positioning, you will further develop skills keeping it in place. It is very much like flying the P4 in ATTI mode. 10WD is about $45, comes with controller.
Outdoors the toy is the Hubsan 502S. GPS, compass, barometer, 720P camera that records to an on-board SD card, with 480p video back to the transmitter for FPV flight. Has RTH features. Absolute blast to zoom around outside FPV with this little guy. $149 direct from Hubsan right now, complete.
