I picked up Heartgold on Sunday.
I've put 13.33 hours into it,just got my 4th badge and getting ready to leave Euckreat or whatever the city is called. I mostly play while watching TV, while waiting for the bank to count my store's bank deposit, during car rides where I'm not driving, and just about any other time I'm waiting for something.
After watching me play it my girlfriend wants to start getting into it and plans on getting SoulSilver on our next paycheck.
As a side note I had restarted Pearl in preparation for Heartgold about a month ago, and have put 26 hours into it, and have only completed 3 gyms.