I fully disagree with people who say, p/s is only good in sw. It's good nearly everywhere, and that is all from spamming only one bugged skill. Only area where p/s lack is burst phase, but that is only couple seconds at the start of every boss fight. if you ask me, I'd remove whole being able to burn bosses from the game completely, unless boss is over 2-3 chapters old already...
That "only a couple seconds" is when a mage does 80% of their total damage on average; even more if the boss fight is short.
I am M/P/S and I played around with p/s burn mode dps, using guitar, spirit water, arcane pot, and a scout's tiered bow (since the fairy gives Rising Tide bonus damage based on bow damage). Frankly, it sucked. I did 1/3rd of the damage I can do on my mage, in the exact same gear.
In my opinion, and I've tested this extensively, p/s is not viable dps in instances. I have used p/s successfully in only one instance, Sardo Castle, and only on two bosses- first and second. That's because Ice Blade is ideal for breaking barrels and also for killing traps on second boss. Now that my group has enough dps to burn boss 2 without doing traps, I take my mage to Sardo instead. There's nothing a dps P/S can do in an instance that a mage can't do better.
P/S geared for healing, on the other hand, is a powerful asset to an instance group. There's nothing better, in my opinion, than having one p/k, one p/s and one p/r in a group. Add a druid into the mix, and you're golden. The diversity of buffs, having the p/k anchor-heal the tank, the p/s using curing shot interwoven with GH, the p/r popping off next to instant urgents as needed, and the druid hotting everyone and using their instant raid-wide party heal is... fabulous.
P/S geared for heals is also perfectly capable of solo-healing a six-man. It's a strong healer.
It just does not have enough dps to contribute in a meaningful way in instances. You can take a mage-geared dps p/s to DoD or HoS and be fine, assuming you are geared for ToSH, but you'll still only do OK dps. Change classes at a housemaid, get on your mage, and look at the difference. DPS p/s is a pvp one-trick pony.