TBH, even if they do remove the cheapest night, and they slightly inflate the price, it might still be worth more than USD 200. I have checked the rate difference at my go-to IC, PLG (in the case I'd want to stay over the week-end, which I usually avoid since I am travelling for work).

best rate for last week-end of August, Fri-Mon: 474 € per night, non flex.
best fully flexible for last week-end, same conditions: 543 € per night (detail: 553, 543, 533).
"free week-end night" rate for the same dates: 560 € per night (detail: 570, 560, 550).

Whether they take zero out the second night or the cheapest night, the total cost would be 1130 or 1120 € per stay, which is still in the worst case 292 € less than a non-flex booking, so the Amb voucher pays for itself. It might not be the case in every property and at every date, but I didn't notice any "inflated price". If you compare with flexible, member rate, it's 20ish € more per night. I also made the same check at the most affordable IC hotel I've been, in Madrid, the price is 264-264-258 for the Amb night (total 781 € for 3 night, that's 522 € for the 2 nights plus the second one free, 528 € for if they take off the cheapest one) while the flex rate is 758 € for the 3 nights and, for non-flex, 581 € for the 3 nights. At the other end of the price spectrum, they still don't seem to overcharge that much (8€/night over flexible rate). If you don't care about flexibility (which is, in my experience, more common when booking holiday stays), it wouldn't be the place/room type combination on which you'd want to use the voucher (since you'd be paying 200 $ for a 58 $ rebate).

With regard to the other benefits, well they depend: if you're new to IHG, you'd benefit from the points by starting at Platinum but there are certainly other ways to achieve it preemptively (status match?) for cheaper. The F&B credit is debatable. Sure, hotel bar have inflated price and it's often cheaper "not to indulge into a useless and probably unhealthy bar tab". It really depends on your spending pattern (I've noticed the bars tend to have actual customers despite the inflated prices so there are some people that will indulge into it sometimes...). In my personal experience, free drink from Diamond is usually useless as a business traveler as I tend to fail to resist the aforementionned upsell strategy and I tend to want to buy something to eat with the free drink, but free drink + 20 USD to pay for a nibble is usually hitting a sweet spot, but that's assuming you're not taking free breakfast as a benefit, which is usually the best choice moneywise unless you can expense a breakfast inclusive rate. Same for the late check-out, it can very useful or totally useless depending on your usual travel pattern.