We visited Sintra as the last of 10 WHS in Portugal, on our varied trip between Porto and Lisbon this July.
What can I say about Sintra that hasn't already been mentioned in the 14 reviews below? Should I mention that it has way too many people especially in the summer high season? Yes, it's like that, at times in the Pena Palace you feel like you're standing in an endless queue at Disneyland. Should I mention that it's still incredibly beautiful? Yes, it is, especially the combination of gardens and palaces really excited us.
But I can at least mention one new thing: You now have to book a time slot for the Pena Palace. You can do this on the website parquesdesintra.pt (in portuguese and english). Attention: The transfer that can be booked there as well is not a transfer from the village of Sintra, but only from the main entrance of the garden of the Pena Palace to the palace itself.