My family 2 adults and 2 boys, 6 & 10 yrs have been to the character meals at Hard Rock and Portofino. The one at Hard Rock just once the one at Portofino 2 times.
I would say it is well worth the experience one time. If you really enjoy it you can look forward to it again next trip. For us I think unless the characters are changed we wont be doing it again.
The kids really love the interaction and I got some wonderful pictures. We saw Woody, Scooby, Shaggy, Beetle Bailey and the Grinch. The Grinch was only there in December and he was at Portofino. It isnt anymore expensive (at least it wasnt when we went) than eating there on a night w/o the characters.
At Portofino they have a seperate kids area with a large screen TV and bean bags, also small table where they can eat if they like with crayons and coloring books. The characters spent a long time at the table and played with the kids as well. It wasnt just sign my book take a pic and leave. I suspect that would depend on the crowd.