IMO, it's the most versatile escort/destroyer ship in-game.
You won't dump out the pure damage of a Fleet Defiant/Jem'Hadar Attack ship. But, you will be able to tank stuff that would blow a lesser escort apart, while doing about the same damage as any escort besides the two I mentioned earlier. Besides that, you can toss out abilities like Viral Matrix, Gravity Well or Eject Warp Plasma that are ordinarily locked away from most escorts.
In my opinion, it is worth the money due to this versatility. I personally used to run one on my Sci character, and while I switched to a Wells class for PvP stuff, the Mobius is still a beast of a ship.
For a little less risk, I suggest that you purchase the Mobius, then transfer your character to the Tribble test server and open the pack there first. There, you can test it out, and if it doesn't work out for you, you can go back to the main server and sell the pack off again.
Get both the Mobius and the Wells, then load both consoles on one of them. I'd recommend the Mobius because you can timewarp bomb with DPB3 -- that locks down all ships around you, leaving FOUR TRICOBALT MINES in your place while you rewind backwards in time and leaving the poor probes (or gate) with no recourse to escape.
It is especially useful against the gate which actually attacks the mines with BFAW.
Look for the link to the mobius under advanced builds, and go according to those lines for abilities. You can do fine with blue Mk XI gear, but use the same versions as detailed. That should serve you well until you can earn more EC.
To eloborate some: I use the MK XI Jem'Hadar Shield and impulse with the MK XII deflector that boosts shields, hull, etc with full polaron weapons. DPS BEAST!
Turns on a dime, making it easy to keep targets in the fore 45 degree arc. Hull and shields are very good. I'd def recommend the Mobius over the Wells. The only other two ships I find myself flying are the Jem'Hadar Heavy Escort Carrier and the Bug ship.
Ghost of Nimbus III. Commander of the R.R.W. Vengeance.