Lets start with my first impression of the Juice Pack Helium. Holding the case in hand, you will immediately notice the premium soft touch finish of the case; it is REALLY nice. The next thing I noticed is that they have finally moved the status LED's to the back of the case versus having them on the bottom. In addition to that, when the case is being charged, the lights will illuminate for 30 seconds but will turn off after that as to avoid being bothersome when you have this charging on your nightstand at night. The last major thing I noticed is that the charging port has moved to the bottom instead of the side which should help out a lot with broken ports like the prior cases.
The case itself is surprisingly lightweight (2.44oz) so it doesn't feel like a brick when installed. The Helium design is pretty typical of their iPhone battery cases which will add length to the device but certainly does not inhibit with the speaker and mic on the bottom of the phone. Starting there, you'll see that the headphone jack is recessed by a large amount and Mophie has included a headphone extender to offset that issue. There is nothing more that Mophie can do about that since Apple moved the headphone port to the bottom. The left side of the case has one large cutout that is wide open for the volume buttons and silent switch; no issues using any of those. The top of the case is similar and has a perfectly sized opening to access the sleep/wake button. Like I mentioned above, the back side of the case contains the status LED's, a button that illuminates those LED's to check charge status and a switch to trigger the battery on and off. The opening for the camera and flash is black lined so it does not cause any flash back.
As for the technical specs of the all new Helium, it packs a 1500 mAh battery which is touted to provide roughly an 80% charge of your device. This will vary of course based on your usage while it is charging along with your phones settings i.e. email push etc. This amount of power should suffice for most users without a doubt. One thing to note is that you cannot sync your phone over the provided wire. You will have to sync wirelessly to iTunes. This should be a non issue for most people especially since most users sync to iCloud over night anyways.
So, with all that being said, I love the Helium case and certainly recommend it. You simply cannot go wrong with a Mophie product. The Helium case retails for $79.95 and is available in 2 colors - Dark metallic and Silver metallic.