This pdf is 20 pages long, 1 page front cover, 1/2 a page editorial, 3/4 of a page SRD, leaving 17 3/4 pages of content, so let's check this Clockworker out, shall we?
This base-class is interesting in that it not only makes for an interesting addition to the Mor Aldenn setting ( I wasn't aware of steam-punkish elements until now), but also in that it provides an alternative to the Summoner that features a different approaches to the base mechanic utilized by the Summoner.
The Clockworker gets d8, 4+Int skills per level, 3/4 BAB progression, good ref-saves, arcane spell progression up to the 6th level from his schematics portfolio (like a wizard's spellbook), the ability to cast with spell failure in light armor, spontaneously convert his spells into mending spells and trapfinding, making the Clockworker a valid replacement for the rogue with regards to traps and the disposal of them The Clockworker has two true signature abilities, though - the ability to create drones and a servitor.
Drones are disposable, small constructs that can execute a limited amount of commands depending on the level of the Clockworker before becoming inert after 0.5 times Clockworker level charges are spent. The Clockworker can deploy these drones 3+ Int modifier times per day as an AoO-provoking full round action. Starting with utility drones, the Clockwroker gets subsequent access to drones that may fly, use evasion, shield allies, carry spells and fight via crossbows. There are some problems with the drones as written, though: Combat Drones don't get proficiency for their crossbow attacks and only get a +4 boost to Str, meaning that their rather low Str-score evens out a now bonus to hit at 10. They come with a basic Dex of 14 that, as written, cannot be upgraded easily, granting the drones a +2 to hit with their crossbows, resulting in a penalty of -2 due to non-proficiency. The melee attack in contrast to the ranged attacks, is a claw-attack dealing 1d2 damage. In melee, the Drone uses either the Clockworker's Dex or Str-modifier and BAB to calculate their attacks. Due to no Str-score-bonus on part of the drones, this is the netto-bonus, officially making the drone-attacks in melee about as efficient as a ray of frost and economy-of-actions-wise, a very bad idea.
Add to that the fact that the drones don't get rapid reload, and, while their damage-dealing capacity in ranged combat are better than in melee, they hit terribly at -2 the Clockworker's BAB for negligible damage and take a lot of actions and we're in for a waste of actions in ranged combat as well. As written, it is not clear whether they carry their own ammunition or whether the Clockworker has to hand them their ammunition, eating up even more actions and making them even less useful. I'm sad to say it, but as written, the drones are utterly, completely USELESS apart from their first level utility functions, minor AC-bonuses (+ 2 per drone, similar bonuses don't require a full round action from other sources like clerics and hold up longer and the drones only get accessible at 9th level) and the high-level spell-channeling powers.
Servitors are the Clockworker's equivalent of a Summoner's eidolon and in stark contrast to the drone-rules, the servitor rules provide the possibility to create small, medium, large and even huge servitors. They also come with 4 different basic forms, quadruped, biped, wheeled and serpentine. The wide variety of different innovations (ranging from 1-point to 4-point innovations, analogue to the evolutions of the eidolon), the innovations enable you to truly customize the servitor, enabling you to create serpentine, breath-weapon using horrors or even you very own siege tanks. To add even further options to the Clockworker's arsenal, he can construct a mechanical harness to benefit from such innovations himself at the cost of his servitor's available innovation pool. The servitor has one MAJOR downside, though: When dismissed by the Clockworker, they collapse into themselves - one well-places charm spell and that's it - the Clockworker has to spend 8 hours reassembling the servitor. 8 hours! While I'm always for classes with some kind of Achilles heel, this particular one is far too easily exploitable and should be errataed/house-ruled, especially with the upkeep cost of the drones and servitors being already a minor drawback.
The pdf closes with mending spells to repair the servitors and other constructs and the Clockworker's spell-list. Unfortunately, the list is VERY blast-mageish/ evocation-heavy. While I do get the idea of the Clockworker creating electric bolts, acidic blasts etc., I think that a class like the Clockworker probably should do such things via his servitor/drones, not his spells, as I do have to admit some balance-concerns here - there's a reason for the Summoner's rather defense-focused, limited spell-list after all and adding Sorceror-style blast capacity to the servitor class-feature might prove unbalancing, depending on your game/players.
Editing and formatting are top-notch, I didn't notice any glitches. Layout adheres to a beautiful b/w-two-column standard that is more printer-friendly than HHG's old standard and even surpasses it in beauty. The interior artworks of clockworks are stunning and of the highest quality, again, Kudos where Kudos are due! The pdf comes with full bookmarks, making navigation of the pdf easy.
First of all: I love the idea of the Clockworker - it's a complex, versatile class with interesting mechanics and great ideas - in fact, I prefer it over the Summoner. Or rather, I would prefer it over the Summoner, were it not for 2 essential problems that drag down what would otherwise be a 4, 4.5 or even 5-star-pdf: The signature abilities just don't work as they should. The drones remain mostly useless things that consume horrendous amounts of actions until they gain access to spells and even then their usability is rather limited. The servitor can be easily dismantled by one botched will-save and seeing that the Clockworker gets bad will-saves, that's a likely thing to happen. Add to that the spell-list that might lead to balance-concerns when the two signature abilities are hand-waved to work and we unfortunately get a class in severe need of a revision.
Don't get me wrong, the Clockworker is far from unsalvageable, in fact, the contrary holds true - with a revision of at least the drone rules and the collapsing servitor-problem, we'd be looking at a high score of 4 or 4.5, perhaps even 5 stars instead. As written, though, my final verdict for the Clockworker, as much as I hate giving it, has to be 2.5 stars, rounded down to 2. I really hope the class gets a revision soon so that I can scale up my review to reflect the ingenious ideas herein.