The one's I've flown in were good for two things: instruments, and EPs. They just were high-enough definition to be good for anything else.
Concur w/ the instruments. Great tool for achieving mins - since we fly mostly VFR section flights, getting approaches is not something we normally do (unless there is slop time at the end of the flight). The sim is also excellent for BI/NVD scan practice, since we're "inside" quite a bit, even on CAVU nights.
It is "okay" for getting a basic feel for aircraft performance in different ambient conditions - high, hot, heavy, for example.
While it certainly has its place, it is not the best tool for EPs, aside from perhaps recognizing the emergency indications that we don't normally experience. Our sim has no provisions for CC/AO assistance, so you go into the scenario losing 1/3 to 1/2 of your crew - not a good CRM exercise, and not particularly realistic training. (That said, CCs/AOs would benefit from such training, as they don't get the EP exposure that we do.) The sim also does not permit to realistically train for most of our "special" missions - externals, HIE, etc. Additionally, as skidkid pointed out, there is really no good way to incorporate a section into the scenario.
Besides - the vast majority of the Phrog EPs/system failures, when feet-dry, are not going to kill you before you have an opportunity to land and figure things out. Remember, we chopper at altitudes that enable us to get on deck in a flash.
When feet-wet, it is more of an exercise in determining landing criteria and weighing your options...again, though, you're normally going to have assistance nearby (since you're usually a section, or at least have HSC on call).
Our best training comes from: 1. Simulations in the actual aircraft, since you can incorporate the entire crew in a "real-world" environment, and 2. Chair-flying scenarios in the ready room (not much different from the TDGs the Mud Marines practice).
Enough geeking it out on a perfectly good Sunday morning. Time for a little Mario Kart.