Well, on a scale of 1-10, I will give it 2 scores.
The Good Score.
Keeping a blind eye to characterization flaws, I'd rate it 7. It was entertaining for the most parts. Mara Jade's plot spanning her quest, her bit of espionage, and the final showdowns were a very fun blend of 'Alias' and 'James Bond'. The scene where she meets the Commodore in his 'den', complete with stereotypical arch-villain's genius madness, was classic 007 climax. Of course, in the end the Commodore is dispatched of pretty quickly and it's a lesser villain that rises in importance, but that's secondary.
The stormtroopers' plot was interesting. I kept expecting one of them to die, though, so the end with them getting off scot-free and intact seemed a little too 'Happily ever after' for me.
The whole over-arching plot with the pirates, the Alliance, and the corrupt governors and deputy governors was intriguing. I may have to re-read just to get all the clues straight. Still, I called Stormtrooper M (can't remember his full name) being related to the Governor. I actually thought he was his own son. :p However, I think the end where the Governor was revealed to be just as evil was a bit of an over-kill, though.
The Ugly Score.
Taking characterization into consideration, and rating the novel as part of an established universe/timeline of characters and situations, I'd give it a 1.
I was never made to care for Mara Jade, the stormies, Vader, or even the Big Three. I barely recognized any of them. Han came out best. Zahn did a good job by showing the conflict he must have felt between episodes 4 and 5 about joining the Alliance. But the scene where Han Solo, smuggler and smooth talker extraordinaire, sings like a bird to a bunch of stormies without stopping to ask them exactly who/what/with what authority they had to be asking him questions... just blew my mind. Nor could I see Han and Luke calmly accepting 'friendly' capture. It just really did not make any sense.
As for Mara Jade: shock! horror! Mara Jade was as Mary Sue as they got. Not only was she brave, quick-thinking, intelligent, resourceful and gorgeous to boot, she was also disciplined, principled, loyal, compassionate and all around, good-hearted. And everyone else thought so. Vader was threatened by her. The Emperor doted on her. (My child??? My child??!? ::stops and thinks:: Who knows? Maybe it's true!). The Commodore remarked on her beauty. The stormtroopers were over-awed by her, and pitied her naivete. ::Sigh::
And let's not even get into the Mara vs. Vader scene which was clearly contrived to show just how stupid, inept and clumsy Vader was compared to the Emperor's Hand. Wasn't that supposed to be some sort of top-secret, nobody knows anything about it, rank? If a quintet of merry Stormtroopers knew the Emperor's Hand, why didn't Mara Jade join them instead of a smuggling cartel? Or how Leia and Luke, her peers needed to be rescued and literally Force-fed respectively as opposed to Mara Jade who always saved herself, saved others and came out of every situation smelling like a rose.
So in summary, as part of Star Wars continuity, it sucked. Big Time. As a stand-alone novel i.e. if you read it as an original work with no similarities with Star Wars, it was entertaining.