+* There's no ``session`` in ORM, so if you want flexibility in some
+ situations not to call ``save()``, and in some -- do call, then you
+ need to implement ``save=True`` parameter in your business-logic.
+* There's no identity-map in ORM, so you need to make sure by yourself
+ that if you modified some object (and did not save it), all later
+ code will use the same object. Also you get additional queries
+ everywhere, and if you have "by id" external links, you can't do
+ quicks optimization by just selecting "most hot" objects once, and
+ be sure they'll be loaded from memory (or do it by hands).