Exactly the ending that was to be expected since a tome or two. The intrigue is resolved very rapidly, and many things are left unexplained, wich is potentially better than weird half-baked justifications.
I don't mind, because it's a thriller and the goal was simply to entertain for its course, but it still barely feels like an end.
3/5
Overall:
Good suspense juggling past and present, with a great look at childhood and appealing characters (à la It). The change in hero for the second era was unfortunate but it partly recovered later, but ultimately the day-to-day writing (extending the group of comrades, resurfacing of others at weird positions, etc) & constant streak of turnabouts started to be exhausting in the last volumes (the third era, under Ami/Friend/Tomodachi's full reign).
Visually excellent, a nice implementation of humour (wich was most needed given the length and dramatic stakes the plot ended up playing), and most importantly an exciting and at times moving ride.
Score: 8/10
Enjoyment: 4~5
Opening the 21th Century Boys book is almost scary. Imagine it's an epilogue featuring a second, worst, conclusion?