Many people complained about Phase Boots being unbalanced, certainly one of the best items for gankers. Others said that a change on the item wouldn't be necessary. It seems that the changes for 6.63 didn't go very well and it will be changed for the next 6.64 version.
IceFrog stated that he started working on the 6.64 map a few days ago (the work never stops). The main thing that is surely making him not able to sleep at night is the Phase Boots with its effects and bugs. Some of you may have noticed a few happenings with this item that should be fixed.
The Phase Boots showed a technical issue that is preventing the hero to be bashed/hit by critical damage while it is activated. This issue is hard to be fixed without losing functionality. Probably, the next version will have changes on both Phase Boots and Power Treads. Here is an idea that
might be
applied:=============
Boots of Speed (500)
2x Blades of Attack (1000)
Recipe (none)
Total: 1500
+70 Movement Speed
+26 Damage
Phase (Active)
Power Treads:
==============
Boots of Speed (500)
Boots of Elvenskin or Belt of Giant Strength or Robe of the Magi (450)
Gloves of Haste (500)
Recipe (none)
Total: 1450
+60 MS
+10 Any Attribute
+30 IAS
Nothing is decided yet, you need to remember that changes like this are always hard to do and need time to be tested. It means that there is a chance that nothing will be changed also.

Links
Playdota - Source