Don't underestimate the power of these little tanks. They may seem underrated at first, but once they get in larger numbers, provided good LOS, they are beastly. They are just very vulnerable to attacks from above, and are relatively bad at turning/retreating. On a side note they cannot be frozen or stoned.

Does anyone use them?

I use them, Clay. When I play Creon, either vs human opponent or vs AI, I always prefer Tortoises over Fire Wagons. I create a Barnstormer or two to have sight of the area and I strike a single target at a time with all my tortoises. Sometimes I also have Automatons in front of my Tortoises in order to prevent Horsemen, Knights, Berzerkers, Spirit Wolves or Blade Demons to reach my Tortoises easily. My Automatons usually die, however they are cheap and serve as cannon fodder pretty well.

Tortoises are pretty good. In one of my unique online games that i played creon i used. I guess Capt remember very well that 4v4, well he just used gs ans drop sage in middle of them and wave. Was a mistake from part of me, that didnt had any kind of air defense.
Btw the tortoise were making such noise for them, when they kill it their life got better. ^^

Torts are best use with the combination of fire wagons IMO. 3 smitty 1 FW's, 1 torts, and 1 barns while you get your academy up.

I wish they could fly