The russin web site mobile-review.com provides very comprehensive review of the E72. If you understand Russian language I would suggest you to read the original review here.
Translation to english can be found in this link. The translation is not that good (Google automatic translation), but it is possible to understand most of the post without any problem.
Another option is to read summary of the article right here 
Following summary of key issues:
- Design and Physical dimensions – Very similar to the E71. A little bit wider and 1 gram heavier. The rubber cover of the USB and memory card was replaced with plastic cover, the red power button replaced with silver button which fits the phone better.
- Display – Same as the E71, QVGA 320×240 pixels.
- Keyboard and Joystick – Keyboard very similar to the E63. The optical joystick works fine and smooth although sometimes you might accidentally click or scroll.
- Voice – The voice quality of the speaker is better. Connector 3.5mm instead of the non standard 2.5mm connector of the E71
- Battery – Although same battery is being used, the power consumption is 15%-20% better.
- Memory - 128 Mb of memory works very good when browsing the internet and several applications running. The E72 recognize 32GB MicroSD memory card.
- CPU – E72 consists of 600Mhz instead of 369 Mhz in the E71, provides faster response and support more colorful interface.
- Communications – Support of UPnP wase added, WIFI is just the same. The infrared port was removed.
- Camera- The 5 mega pixel camera provides better pictures, no detailed information about this issue.
- GPS – Digital compass added which provides the positioning of the map according to direction of the phone.
My impression of the post is that although the E72 is better the the E72, it has only some improvements and not a completely new phone.
