Activity points are screwed as of 1/16/2014 - no longer possible to get 50 points a day without PVP or grinding out all the daily quests-which also requires PVP. (Unless I'm missing something). Waiting for PVP takes too long. At least before we could limp along and earn a purple card every 7 days...
Buggy - in final level with first Grand Walker, i dragged a cannon down to upgrade it and the action froze; music still plays and I can sell things, but cannot buy/upgrade/unfreeze anything.
If your spell icons disappear (the ones you get by clicking your hero), you probably have to quit and reload the page to fix it. Irritating annoyance; otherwise a very nice game.