This is the second version of my review, after giving it some thought.
I still feel this came out to be a mediocre product, honestly. The price may be right for some, but running down...
The interiors are pretty. It's a pretty book.
The conversions of the major "splats" for each gameline are fairly simple and not anything most hack-minded people couldn't come up with themselves, aside from a mildly interesting take on the Avatar background as a Merit (it alters certain aspects of your Gnosis).
There are simple rules for Ascension's customized foci as a replacement for Awakening's High Speech and brass chalices. They're workable, though I found the Magical Styles system provided in the Mage Chronicler's Guide to be a more effective system for unique magical methodologies. There are rules for beefing up rotes in Ascension to the level of Awakening's rote spells, which were satisfying.
A lot of rules are, effectively, copy-pasted from one gameline to the other with minor tweaks, and again, aren't anything somebody already inclined to hack two gamelines like this couldn't figure out on their own: Legacies for Ascension, the aspects (vulgar/not) of magic, and (glaringly) the translation between Arcana and Spheres and the Paradox systems (Awakening's Paradox systems converted to Ascension fare a little better than their counterpart). This is by design, but the effect fell flat for me.
Certain other rules are so vague as to be almost superfluous, such as those for Marauders and the Mad.
The translation of cosmologies and invisible worlds fares well, as does the translation of spirits and the introduction of the Tremere Liches to Ascension, which I think hold a lot of potential.
Overall, a lot of the major features one would come to this book for, I feel, can be done without it just using the twin Mage corebooks and a little spit and polish. (Do not actually spit on your books.) I can't really recommend it, but your mileage may vary.
[3 of 5 Stars!]