Just a couple of add-ons that others mentioned:

If your GA experience is from pre-9/11, watch out for the TFRs. What used to be a quaint backwater of the AIM seemingly limited to forest fires and hyper-intensive oral exams, is now a giant PITA. If one pops up, it can shut down your whole show for hours at a time, if not more. They can also snare the unwary.

In theory...at least what the local CFIs say, is that an online briefing from DUAT or Leidos website (used to be LockMart) is the same as a phone brief as far as covering your tail for TFRs, but who really knows. I always follow up a on-line brief with a quick call to Flight Service to check.

I came back to GA in 2011 after 20 years gone...pros and cons:

Pros:
GPS
iPads + Garmin Pilot/Foreflight/Your favorite App flavor here
ADS-B/Sat WX
ADS-B Traffic...this is a new one and IT ROCKS!
24 hour self-serve fuel
Cell phones (ever run from a payphone to make a void time?)
Internet weather/filing (I was flying about a year before dial up DUATS became a thing...1200 baud FTW!)
Engine monitors

Cons:
TFRs and overall hassle
LOTS more towers. This might be bad or good depending on your perspective.
Can't fly into DCA (I know, like you were before, but at least you had the option)
Fences and getting trapped at an airport at night (call ahead...fuel might be 24/7, but the gate might not be).
Costs....gone WAY up outside inflation
No one around. Far fewer props turning. The bonus is that there are fewer idiots because there are fewer pilots overall. But 10% is still 10% so keep a look out.

Nu