I visited this WHS in December 2015. I drove from Palenque to Tikal by car through the El Ceibo border. Tikal is definitely Guatemala's highlight and one of the best WHS I've visited so far. The rainforest environment is still intact although the central plaza has been cleared. However, 'VIP service' buses/vans should not be allowed inside the historical area proper as is currently done from the back roads for the older wealthy tourists. However, apart from this practice, the main ruins are spectacular as are the minor ones still full of scrub and overcome by the jungle. Tikal is the best preserved example of an ancient Mayan city. Climbing is prohibited mainly on Temple I although access to the other main temple structures is gained by climbing wooden stairs on the back of the structures. As always, birdlife and fauna is most 'active' at sunrise/sunset. It's worth staying at least 2-3 days to be able to enjoy the park at different times of the day. The sunrise hype can easily be skipped as it's the only time when the site is really packed and since it is frequently misty, there is nothing you'd miss if instead you stay in the lodge in the national park (except the crowds and the early wake up call at 03:30!).