I jumped back into active GA flying about three years ago. At that time I had only logged about 5 hours in GA aircraft over 15 years, as compared to my airline flying. It has been great fun to go back to that part of flying and well worth it. That is a part of flying, seeing the landscape close up, at a leisurely pace, no schedule to keep, anywhere you feel like going, that you don't get in the airline. A lot of my airline friends whom I take in the Cherokee feel your apprehension. This is what I think:
1. Takeoffs are no problem, the landings at the correct flare height take about 10-15 hrs to get down.
2. Airspace,,,remembering Class B, VFR wx mins, fuel reserves at night
3. TFR's are now a part of preflight action, plus the fact that they exist over major sporting events.
4. Avionics of the new acft. Garmin GPS/Comm's, Autopilots,,,often as complex as any modern Boeing or Airbus,,,will take time to learn.
I recommend this - go online to AOPA, or ASF (Air safety Foundation), they have plenty of free online tutorials that will get you up to speed on regulations/airpace/fuel as well as links to online avionics trainers. Then go to a local GA airport and hang out with the instructors. Find one you work well with and go fly a few hours on landings/maneuvering.
We have had so much fun in the Cherokee over the last few years, it's a different segment of flying you completely miss in the airlines.
Have fun!