I know most SCs are overpriced to some extant and Tet seems like he's apt to be no exception, but if we let that stop us, we'd never use SC. It also seems like a fairly fun kit bash to do. Eye of the Old Ones sounds like a really useufl item. Problem is skinks seem like a very very weak bunker. Who used Tet successfully? Who regretted fieldling him.
I have used him maybe 4 or 5 times. He is worth it on the loremaster and reroll on comet alone! The skink bunker is not really a problem as he gets a look out sir and you can always make it a horde unit ( I will keep that unit out of combat as much as I can though). Another useful rule is the redeployment of d3 units. Although, I admit, I forget to do this usually. The item that lets him IF a spell on a double has done little or nothing in the games that I have played. I think it may have worked the first time I tried him out (7th edition I believe). Anyway, he is a fun SC to take. I recommend taking them all at some point, just to try them out. Even if they are expensive, they can be fun to play.
I played Tetto'Eko in the 'Ardboyz semi-finals. The redeploy won me my 3rd game. My army was: 70 Saurus horde, 26 Templeguard + a Slaan 2 salamander units X2 8 Chamo Skinks X2 10 Skins with blowguns(bunker for Tetto"Eko) 1 Oldblood 1 Scar Vet 1 Tetto"Eko I was playing against a triple Hydra DE army and due to the redeploy I moved the horde of Saurus across the board. The DE player ended up with 1 Hydra and a unit of spearmen all alone and all of my army in front of his wizard's unit. For a smaller game, the 255 point pricetag is a bit steep, but he works well at high points values. I would not run him in a unit of ranked skinks. He is only M4, so he slows them down too much. I prefer to put him in a unit of skirmishers and hide behind my blocks.