A new in type private pilot aboard his PA46 lost control in IMC conditions and gained and lost multiple hundreds of feet of altitude while recovering.

Narrative

This was a low IFR day. On departing for the second leg of the trip while on climb out and vectors to en route I was climbing into glare and variable cloud decks. I believed I had engaged the auto pilot to decrease work load and to facilitate the next portion of flight. I looked down to adjust the GPS and when I looked up the airplane was in an unusual attitude. There was a passenger on board who was a private pilot who no longer actively flies. He at the same time pointed out the attitude issue. The combination of the situation (IFR; clouds; mist; glare) and the unusual attitude combined to result in an inappropriate horizon illusion which was actively fighting against the instrument readings.I leveled the wings promptly; but with the visual illusion and my recent upgrade to the plane and avionics adding to the situation; took an extended time to fully regain heading and altitude and overshot to 3;300 feet on a 3;000 ATC limit; also lost 500 feet to 2;500 and also took additional time to regain proper heading. I have never previously experienced an illusion of that intensity.Factors that I believe were important or contributory: 1. The need for more time in type; and with the aircraft avionics which I felt I had become well familiar with; but whose operation are still not automatic or second nature. 2. Better focusing on flight path control during these phases of flight as opposed to multitasking. 3. A need for more IFR practice in this airplane with a safety pilot or instructor to better learn to utilize all resources and instruments appropriately during periods of high work load and competing tasks and stimuli. 4. A better approach to minimize and recognize the possible optical and sensory illusions that can occur in spite of no previous issues with similar situations. 5. The need to re-set personal IFR minimums back upward till I've more time in type. 6. Better recognition of the hazards of becoming fixated on avionics during a time when the control of the aircraft is the first priority.