The worst part was the month during which I thought it was a physical medical condition, and the absolutely rotten quality of treatment I got in many cases. One example was (during the worst attack I ever had) a 7-hour ER wait, including 6 hours locked up in the psych ER, without being told why this was happening. Once I was able to see a doctor (1 doctor on staff for the whole psych ER) he was able to explain what was happening and why, but even then, all he could prescribe was Buspar, which doesn't do anything for panic.
My experience is that the attacks don't go away entirely, but they become rarer and much more manageable. The depersonalizing attacks that feel like bad drug trips don't happen anymore for me (and stopped happening once I got appropriate medicine) because once I get to a 4 or 5 (heart racing, painful muscle tension, inability to concentrate) on the panic scale I can get it under control, taking a benzo if necessary.