I don't expect their ORM to be perfect, but it's probably the worst I've ever used. Not in regards to the queries you can/can't run with it, but because of the way it's not really OO -- you can use it in this psuedo-oo bastardization sometimes, but in general you use a model "object" that's built into your controller, and on that you call methods like read() with some conditions. The read will return an associative array with your requested data in it. No iterators, no objects, no methods, no way to call methods on it because it's not an object, etc. In addition, when you call read() it not only returns the data but also populates the controller class $this->data array, which, along with the returned array, are always keyed off the model name you called, so you get these two twisted copies which are also shared with form submission data so it's a huge cluster**** nightmare. Your resulting arrays end up looking something like this:
And you pass this huge array around to the various model classes who by convention only look at their associated key, although that's not entirely true in some cases if you have some associations set up. Of course, none of this is transparent and the document refers to everything you pass around as $data or $options and rarely if ever actually go through the various keys you can set in $options (and of course, if you mistype a key there's no error checking as you'd get with real named arguments or function/method parameters so it basically just ignores it if you happen to fatfinger something).
Anyway, their url mapping sucks, too, as does their really, really crappy form validation. I've been using it for ~3 weeks now and the more I use it, the more I dislike it.