The announcement may be late, but the update was on time, and that's what matters. ;)
The Valentines day update introduced some new scenes heavy on romance, a new good ending, and generally added more pleasantness to the otherwise vile world of Sickness.
The additions and changes include:
-1 new route, which results in a “good end”, and covers a new romance
-10,000 words added, bringing the total word count to 138,500 words
-3 new CGs, 2 of which have variations
-1 new variation of an existing CG
-1 CG (and its variation) have been updated
-5 new music tracks
-8 existing backgrounds (+ daytime variations) have been replaced
Replacement backgrounds will be added incrementally from this point on, as there are still a few inconsistent backgrounds that need replacing. That was the plan from the beginning, but since this update was ready so soon after release, the new backgrounds were instead packed into the update.
There are also 3 more big updates planned. They will each take longer than this update, however, so it will likely be a few months before the next route is added. I haven't decided on the order yet, but most likely:
-Update 1 will be an unlockable extra. Rather than adding new content to the main game, it will essentially be a side story, covering many events for which Suoh is not present, and revealing information he never becomes privy to.
-Update 2 will include a new route, and at least 2 new endings. It will also change certain important events early on. It's difficult to elaborate any further without providing spoilers.
-Update 3 will include 2 new characters, and will have a very big focus on the back stories of Sara & Suoh, answering many questions about their past. This update will once again contain at least 1 new route, with at least 1 new ending. It's also a bit bigger on romance, so... perhaps Valentines Day 2017?