1) Muramana - nothing special abut this item, because it has active and that active ( 6%mana as ad), is not much stronger than old manamune 4% which was passive. Only base demage was buffed by 10 ad what is not bad. I liked more old one because it had passive effect.

2) Spirit stone - feels weak. I tryed diana in jungle (with spirit of spectral wraith) and was struggling with this item and it didnt gave me any good stats for fighting out of jungle. Dont see reason to upgrade further from machete.