5. Too expensive. Part of this is long term effort and troops needed to go the full distance. Ties in with #1.
It's fun when you're making progress, but the endless-back-and-forth fight for sectors is a huge turn off- way more than initial fun. There's a ton of fun games out there completing for time, and the slog isn't worth it.
If you can't buy a mansion, is it too expense or are you buying outside of your budget? Straining wallets means you are out of your league, and you can just as easily be out-classed by attack/defense boosts as you can a guilds wallet, meaning that if you are having trouble, you'll likely have to operate in a lower league.
Also...this is the first game and so I don't think many people realize they will have to do this over and over and over again. I might have underestimated peoples abilities to produce resources, but if not, I think that negotiations will cease to be a primary method of pushing GbG when people begin to go broke. It's largely because of the demand for previous-age goods- which I feel the Star Gazer is inadequate to supply. People will burn through their hoarded stock and then...we'll see. If that is true, the game will go through two major phases of categorizing guilds in leagues- the initial phase we are seeing, and the one where sober recognition of the long term costs see those guilds who cannot maintain their rank without mass-negotiations diminish in rank and so the sifting process may be a little longer than expected.
I think it is the long run that will determine the future of the game. This is the first run and it being brand new, it has it's highest participation rating. But it is pretty intense. Activity and enthusiasm seem to be relatively high over a higher portion of the day rather than with GvG where things rev up around recalc. No matter what you say, the best thing about it is that you will generally find yourself operating against people of a similar caliber as yourself and while you might not always be the grand winner, no one who participates loses. Even discounting the final reward, there are pretty good rewards simply for fighting. You get fp, troops, a chance for diamonds... I make 350 fp a day and still find it pretty useful to get that occasional fp reward from fighting every once in a while.
In the end I actually like it and I think there's still things left to discover in this feature that will keep people interested for some time.