Chopping is phenomenal, as is harvesting resources in bad locations.
As for pyramids, they cost 220p, give you 2 culture a free worker, +1 charge to every worker, tourism, and maybe a theatre district adjacency.
A builder and a Monument would cost you at least 110p, build this instead of those and you're spending 110p for +1 bonus charge to every worker and the future tourism. If you're France or (particularly) Egypt, you also gain up to 3 adjacency bonuses for your special improvements (9 culture for France and 3 culture and 9 faith for Egypt). Egypt also saves 15% of the cost, so 93.5p for all these things. Less than two archers. Not bad at all, it's kind of a steal, actually, so long as you can afford to spend those extra 10 or so turns on it. Of course, if you have extra forests and jungles around to chop it out, that is a great option, since you'll be rolling in builder charges afterward anyways it's a pretty solid investment. Now instead of taking the time and production to build yourself a monument and a worker, you have yourself the Pyramids at only the added cost of a few forests (the builder to chop them is almost irrelevant).