Observations from most recent playthrough as the Hutt Cartel:
Bootana Hutta: Pay once to train a ship (possibly discounted, most ships, not all), pay again to store the ship (cannot be discounted), pay again to use as a defensive upgrade (no discount, takes quite a bit of time) IF you have a shipyard. Then, the ship ... might be lost? retained in the pocket space? Not sure the intent, had both happen.
Also, if you call in those ships, better have a minelayer interdictor or the attacking fleet is just going to run.
This mechanic is satisfying only when the AI attacks an already fully defended space station, which is rare.

AND this mechanic must be used to unlock "Hutt Mobilization", which includes needed starfighter upgrades, a hero, and ships.
These all seem pretty decent, but don't expect Hutt starfighters/bombers to outperform the other factions, even fully upgraded.

Scum & Villainy:
Unlock heroes via smuggling operations.
Heavily weighted towards the end, feels like this should be better spread out. Smuggling prioritizes certain "rich" worlds (anything under 300c/cycle seems trivial), costs money to start, and is eventually cancelled out by conquest.
In exchange, the Hutts LITERALLY cannot tax their populations. Comes across very gimmicky as you must do this to unlock a lot of heroes (of varying quality), it has little effect once you've completed the cap, you're better off conquering planets that you can put mines on, and it has no effect on a planet after you conquer it.

In both cases, added Mobilization or S&V from missions is pathetically low and not even worth considering.

Ground forces: emphasis on repulsorlift is an interesting concept, but lacking any heavy type vehicle hurts, and Luxury Skiff is underwhelming for size and cost. Might work if embarked infantry could fire while boarded (not sure on those mechanics). Also, 2 AV fliers seems poorly balanced, especially for a race accustomed to putting down slave revolts who tend to be "I" vice "V". Frequent Cloud Car mission rewards addressed this somewhat.

Commanders via mission only might have been more tolerable had I not received an Airhook commander every time.

Space Forces: missile emphasis is interesting. Of course, there are a lot of inefficient ships that should just be avoided, and others that are best (seems that way for every faction).
The Dur'balla is a plain, but quite serviceable capital ship.
If intended to actually capture ships in a time period with few Ion Cannon hardpoints, Hutts should have SOMETHING to assist in this endeavor (starfighters with ion cannons, loadout swap on some ships, a temporary disabling shot, a better invulnerability) or else this is just a distraction that costs credits and pop cap.

Overall, the Hutts seem to be a bit of a "hard mode" in they do nothing particularly well, and fall behind in several cases.

I suggest emphasizing their wealth by making smugglers have a persistent wealth effect after conquest, add a fluctuating cycle bonus for Smuggler Dens, and make Bootana Hutta more predictable (vice seemingly glitchy). Also, being able to select pirates would help considerably.

EDIT: Hutt Hero Tank commander has speeder bikes for his escort (this is odd, but acceptable), but he is also a "Space" commander, which makes no sense at all.