The book gives a good overview to Elven life in general, altough
some of the information is not realy necessary for an accomplished DM.
Beware: If You realy plan to let Your players have their way with all the extra rules given (Str:19 for Sylvan Elves, Bladesinger Kit and Bladesong rules are the most notable),
You'll end up with a threshing machine that can easyly outdo
the rest of the group as a whole and won't be able to find a suitable challenge only too soon.
From level 7/8 onwards, a Fighter/Mage with the abilities mentioned above and equiped with a Stoneskin/Fireshield/Haste/
Mirror Image spell-combo becomes nigh-invulnerable in close combat and will deal out amazing amounts of damage.
So I recomend to be very carefull with these abilities.
In the hands of a strong-willed PC this book endangers the ballance of any campaign.
In the hands of an accomplished DM, it can give a lot more depth to Elven life and culture.