For regular players, the level 27 release was probably a bit of a disappointment – no new decorations, and only one new premium item in Mount Carlmore. And despite being a fan of the premium items, I’m really ambivalent about Mount Carlmore, as you’ll see.

First, the reasons to buy it:

1. It gives you a 3.5% bonus on all your cash and XP collections, no matter where you place it.
2. If you place it near Springfield Penitentiary, Lenny can have something to look at while he spends some time there in Lenny’s Downfall.

And, really, that’s about it. There are far more reasons not to buy it or to buy it later:

1. It’s not a limited-time item so there’s really no rush. There are better things to spend your donuts on so if you don’t have them, buy them instead. You will always be able to but Mount Carlmore in the future if you decide you want it and have room for it.
2. Thankfully, Carl and Lenny came together with the Springfield Buddhist Temple, so there’s no reason to buy it to get a character – in fact, placing Mount Carlmore doesn’t release any new characters at all.
3. It’s large and awkwardly-shaped and rather difficult to place, with colors that match none of the decorations available.
4. As one person has already pointed out (and sorry, I can’t find the comment), you can buy 3 police cars for the same price and end up with a similar XP and cash bonus (at 2% each car)!
5. It really belongs in West Springfield!

So, my advice would be to save your donuts for now – there are other items that are better value and that give you greater enjoyment in your game. And there may well be other things to spend your donuts on in the near future which are much closer to being “must-buy” items.

P.S. If you do buy it, this is what you see just after you place it: