I know its new and balancing changes will come, but for now:
1) by the time i can afford mote merc ships i no longer need them
2) Many bonuses are just not worth the cost e.g. I purchased a ship that added bc to a world (forget the name & exact #'s), put it on my best $ generating worls and it was going to take like 100 turns to recover my investment.
3) several bonuses are about the equivalent to only one improvement building
Not all bad
a) I have used some of the early survey mercs and they worked out well,
Early +research ,+mfg, +shipyard mfg can be useful (good) but hard to afford
Haven't tried getting a early fighter or the one that lets you invade pre age of war, but might be cool to launch an early strike against an AI
* not bitching, really like the idea but i think it need balncing