The content we're gaining doesn't seem to justify the large chunk we're losing. For perspective, we're gaining 2 Strikes(1 Recycled), 2 Raids(1 Recycled), and 2 Zones(1 Recycled), with 2 more Recycled Strikes coming "in year 4". We're losing Mars, Io, Mercury, The Leviathan and Titan, 7 Total Strikes and 5 Raids, and a FUCKLOAD of Exotic Quests, Story missions, and other content associated with those zones. Not to mention the Expansion is $40 not including the Season pass (which is "only" an additional $10).
Edit: Also, not to mention full on activities like the Menagerie, Forges, and such