Ok so I ran a playtest using the Occult Mysteries classes with a few friends. Our heroes are as follows!
Jenny the Mesmerist
Thalamon the Kineticist (Aether)
Yuuji the Spiritualist
Shoko his Phantom (Jealousy)
Lysandria the Occultist
Character creation went well the Kineticist was ecstatic with the class and all the choices. Our Spiritualist really enjoyed making his character and grabbed Cure Light Wounds as one of his spells knowing the rest of the party's makeup. The Occultist was torn on what to choose but wound up going Abjuration and Transmutation starting out with a Greatsword, though she debated going for Evocation. Our Mesmerist had the hardest time making her character she wound up picking the Psychosomatic Surge to help offset the low healing power of the group.
To summarize the adventure the Kineticist was the absolute star of the adventure. He dominated every encounter with his blast alone. I don't think he used his Wild Talent if I recall. He was still just completely enthralled with the playstyle of the Kineticist and is jonesing to play one in my next full game. He looks forward to later levels playing with Burn and other Wild Talents.
Followed immediately by the Occultist buffing her AC and Weapon through her mental focus. Part of that she felt was due to the Greatsword being an amazingly strong weapon at low levels. She did feel that she didn't have enough mental focus at the 1st level to burn it and activate her weird powers. She didn't cast much, mending a few times and open/close. She did use her disable device skill several times throughout the dungeon
Our Spiritualist while not as much the combat monster as the previous two helped a lot on the utility side of things. He used his Phantom to great effect as a scout sending it through walls and doors before the team entered to get an idea of what they were walking into. The time he failed to do so the Kineticist took a Javelin trap to the chest. The Phantom provided an extra body to soak hits which helped a lot. He mostly moved around to flank with his spirit and did all he could to spread around the Jealousy Phantom debuff.
Poor poor Mesmerist. She was not happy with how the character performed. She used Daze several times, a crossbow a few times, and attempted to use her Trick as often as possible. Her feedback after the session was that she felt completely useless. She said it would probably work amazingly in a City or Social setting, but in a Dungeon she felt at a loss compared to the other players. She also said the Trick duration was way too limiting. Having only 10 rounds for her trick to trigger only in specific situations. 2/3 of the time the combat ended before her trick triggered as the Occultist, our primary melee combatant, wasn't hit as often as expected.
From my vantage point as GM at first level the Kintecist seemed to be the winner as far as using it's Cool Schtick and being effective at the same time. The Spiritualist seemed to do very well, myself and the player likened it to a low level Summoner with an Eidolon focus though so it may need a little more weird to stand apart. The Occultist didn't give a really good feeling for it's weirdness, the player really wished she'd gone with Evocation to have maybe a bit more weird or power usage in there. I concur with the Mesmerist player that it seemed to have the least effectiveness for the party, the limitation on Tricks were brutal having to be a triggered and only in a certain duration. She also kinda wished that the Hypnotic Stare may have affected something in addition to Will saves at first level, so she could debuff a bit more and help contribute a bit more.