Personally, to me the game is boring. I already said this before, but the lack of content, the long down time between events, and the constant PoC 2 days grind is as far as content goes, lack luster.

Many tanks I have still lack stories - which is another thing that can keep you going for a while, but when there are none.... well damn now what ?
If the game doesnt increase the content variety, I will slowly drop it once Girls Symphony returns on DMM (should be just few months away now, we already got a notice from the new team). The game has some good things going for it - its very generous, the event tanks are actually pretty good compared to other games event units, the BASIC art style of the girls tends to be very very nicely done (especially on heavy tanks the armor looks good), but over all, the problem with this game is - once you clear the main story and get the tanks you wanted, clear most of the character stories and equip your main squad.... there is not really much to keep your interests.

For example Flower Knight Girl, (on DMM that is) has multiple layered story lines, many different missions types, some of which require you to rebuild your team completely to fit, older events are re-issued periodically, the main story line missions are slowly being added, ALL the girls of 5-6 tier have theri character quests and at least 1st H scene done, (not sure about the chara. quest with lesser tier girls, but ALL of them have H scene if nothing else) and overall there is so much stuff you can do you that its actually impossible to get everything done at the same time, and you need to decide what to do and who to keep for next time (as you lvl up and get more Stamina per lvl this helps a lot in the long run).
So the game is actually never really boring. And doesnt feel like chore. Something I have actually felt when playing AB - especially with PoC and the boring event missions which offer zero variation.