I suggest the tarantula get's more damage reduction and hit points. That would make it work more in every aspect.
Kall

Back in alpha, before I got too annoyed by the bugs I just mentioned that makes using turrets basically impossible

(except you want to wait the 60s next to your turrets after every use so they despawn properly and you can cast new ones),

I tested them in various situations, and the results were:

- pretty much useless against horde and regular mobs (activation and target acquisition are far too slow!)
- mildly useful against champions (depends on many things, early/later game, players dps,....)
- pretty useful against boss mobs (elites), IF and ONLY IF used right (don't let them get hit)
- HP are far too low, you need to be extremely careful how/where you place them, or they die instantly, especially in boss fights
- dmg is overall good (we are all used to onehit everything due to so many things broken in this game, their damage is quite ok-ish considering that)

But as I said, before one would go and tweak turrets to make them really useful (faster targeting, more HP),
they would need to be bug-fixed to be even usable at all.

I still dream of the day,  when my crusader, pumping 5 focus/s, spams mobs to death with turrets casting on cd... one day!

How about the fact that half the time the turret faces the opposite direction of the mobs most of the time and never swings around to shoot the ones behind it. 

Too high focus cost?

It's the only one of the 3 crusader armor skills that would be actually good for dumping focus to heal HP/SR!
(with 3+ focus/s which is easy to do)

Well, it would be, if turrets would not be completely unusable due to the 2 turret bugs:
1. does not despawn
2. can't cast new one if you have 3 (oldest should depspawn in that case)

Broken since alpha, and I am still waiting....

Turrets are only good in pvp for ravaging opponent supression

 In pve turet is kinda useless,  it just take alot of time to depoloy and start fire, when it start fire you alredy killed enemy, manualy even on red dificulty.  Also focus cost is high per  turret according how bad it is for pve,  cooldown too.  

Overal game is so much dynamic for turret playstle

I always felt a turret is better off dropped before the action ensues instead of after the action starts. Agreed that it does take a minute for the turret to focus. All the better reason to drop it early. Had many many times I dropped it, sat back and let the turret do all the work.

Everytime i've gone with a Turret last about 5-10 seconds before it is utterly demolished into dust, and i might add the first few seconds it seems like it's machine spirit is on drugs, just standing there doing nothing -_-

Really? I've consistently had the best luck with the turrets playing tactical. Missiles are useful for killing horses I guess, but I already have AoE guns so it's redundant. Likewise I can dash if I want to use a greataxe, while turrets can be consistently useful throughout a fight against any opponent. I can use them to tank for me and draw fire when I've been hammered, or I do the tanking when I'm full up and they just keep putting fire on a boss so any regen never triggers. And with the focus boosts from gear, I can have three of them dropped in like 25 seconds.

I dare you to attack me when I'm turtled up that way. Defence missions are a cakewalk with them.