There's the good and the bad.
What the guidebooks said came to pass: We were conned by people outside the Palace (claiming it was closed), when they had an "understanding" with the tuk tuk (tricycle) driver to drop us off at the side of the Palace that was closed. The "guide" then regaled us of a palace that was open, and after that, the tuk tuk brought us to a jewelry shop.
With that unpleasantness out of the way, I can say that the palace deserved its name: Grand. It was huge, house and corridors after one another of amazing architecture, and devotion to their gods and ancestors was so apparent. It is a place that can make you feel enlightened - were it not for the thousands of tourists jostling for camera positions, running to and from their assigned tour group schedules, and what-not. We went in August 2007, admittedly a "touristy" time.
What surprised me, considering the fact that there are millions of tourists who go through Thailand each year, is their weak English skills. I realize as a tourist, I have no right ot impose my language on them - but their counterparts in Asia (China, Hong Kong, Singapore) all have better English skills, which left me wondering considering the amount of business they get from the tourism industry. Even shopping in the malls (I went to Nike in Siam Paragon) was a chore - they couldn't understand basic words like "How much?".
And their oft repeated claim about being "The Land of Smiles" just didn't turn out to be true. Many of them were downright surly or rude. (I've been to Guangzhou in China, which isn't really a must yet on anyone's tourist spot list, but despite the lack of sights, the hospitality I received thenre more than made up for that and made it a better traveling experience than the one we had in Thailand.) I have been to Japan, Taiwan, the USA, China, Hong Kong, etc., and Thailand really ranks the worst for me in terms of "customer service".
Thailand really has some of the most spectacular sights (like the Grand Palace). The human factor was the big letdown.