Not mythical in my case. I renewed yesterday and it now shows Diamond expiry 31 December 2024.

Detailing Admiral Ackbars post above

• Guaranteed 1 category upgrade
• Varies in value by property. Some interpret as a higer floor but effectively same room - or not facing a road. Others will be significantly better equipped rooms or even suites. Out of 8 IC's so far this year IC O2 London did the minimum as did Istanbul and Sydney . The two Bali properties and KL really delivered with suites and even a Villa!
• Guaranteed 4pm late check out
• Can be very useful for late flights when combined with a lounge pass or preagreed deal to only use lounge on departure not arrival date
• $20 F&B credit
• Surprised how infrequently I actually use these given I have a Lounge Pass. Prices for beverages can be so ridiculously inflated (IC Stanford HK is nutz) that I resist the upsell strategy to buy more - which is what I suspect was IC corporates sell to the hotels. LOL
• One free weekend night
• Well yes. But it is the cheapest night. And the base night rates are invariably inflated significantly over BAR. And many properties are being very cute at ensuring the lowest night of the "weekend" 3 is significantly lower than the adjacent 2.

I just renewed. But it was marginal. I'll likely do 10 IC stays and about 30 nights in the next 12 months. The 15000 points for renewal made my loan of US$200 likely viable. Where I might lose is I can't see me availing the 4p checkout very often. I have used it 4X in the lat membership year. BUT I have also gifted 3 very early checkouts from premium rooms.