What about the other tanks

[Gammagulp]

I also used ghost tank some time and you said the same things I experienced. I used life heal (soul restore) and ghosts, but the ultimate is really difficult to use and sometimes even useless. But I want to disagree the point with the air. For every try to hold an airtank you have to pay 200 Gold - thats pretty much if the enemy goes on early airship ang gives just 280 or 290 Bounty. The Plasma Rain is not good for your troops and ghosts.
If you face a Sky tank its even worth, because the whole AOE Ground spells it can use even if it is in the net. If your enemy does not he was not the same good Skytank I had to face, when I played gfhost before.

I think its playable, but needs a lot of skill and good Itemcombination to get it into real good use. Against demon with Poinson magic - hmmm in teamplay its ok, but 1on1 you can really lack, because if it uses stun and AOE short range ultimate good with maybe own troop command you can be dead really often as you have only little speed and demon got far more HP.

The lifleech is good against air, that cannot stun you, but usally air gets fast out of range and you cannot hold the enemy long enough for a good leech. The ultimate ... well, we already said everything ^^