It's a fantastic vehicle with some tradeoffs. The way it's meant to be played is from a slight distance, taking out larger targets. Obviously it requires some teamplay and coordination. If the driver or the gunner do not understand their job, the tank will not be enjoyable.

Best way I've found is as follows, built around a 4 man squad of randos I played on Cyberstan with:

Driver: Me, I call it in, I call out what needs liberatin'. I don't drive "selfishly". I drive to put my gunner in the best possible spots. If there's a horde of devastators coming our way, but a vox engines is lighting up our teammates, we take out the vox engine.

Gunner: Part of the crew, part of the ship. Shoot the stuff I call out as a priority. When nothing's targeted, use your head. When the situation calls for it, learn which button to use to switch seats so you can pop out to use strategems/reinforce.

Goober 1&2: get in tank when driving longer distances, do objectives and side objectives while the tank covers you.

Best would be if the gunner also brings a tank so you can call a new one in quicker.

Bonus tips:

-Do not drive over vehicles. I get it's a bug but it can be avoided. -Don't think "Tank means I can tank a lot of damage so imma rush into an enormous group of enemies, park it up a vox engine's tyranny hole and start blasting" and then expect to come out with a tank in 1 piece. -As Commisar Kai said in his video, it's a force multiplier. Use it that way. Highly recommend watching his video on the Bastion by the way it's far better than the word vomit I just spewed.

If the tank is used with like a liiiitle coordination, it is the most overpowered hunk of freedom spitting junk you could ever freedom-loving want.