This pdf is 13 pages long, 1 page front cover, 1 page editorial/ToC, 1 page SRD.

That leaves 10 pages of gaming material which are, as I’ve come to expect of Spes Magna Games, well-edited and printer-friendly.

The idea of Ars Metamagica is, that one abolishes metamagic feats and replaces them with a new system that actually gives metamagic some game time and makes players use it:
Modifying spells is now done via a kind of caster level check that depends on the metamagic art you apply to a certain spell. If you fail the check, you have might experience some repercussions, depending on how bad you failed: 4 or lesser means that the spell works without metamagic, 5-9 gives you temporary ability damage and a failure of more than 10 fatigues/exhausts you and might even deal subdual damage, if repeated.
Every Caster gets a selection of slots every day called “Metamagic palette”. If e.g. you have a palette of 5, you could choose a metamagic art with a value of +3 and +2. Or 5 arts with a value of +1.

You can also leave slots on your palette open and meditate 1 minute per +1 to fill them semi-spontaneously.

Both preparing and spontaneous casters are addressed and the pdf also takes the metamagic feats from the APG into account. The pdf takes several factors into account and offers revised version of the bard spell Arcane Concordance, a new universal Metamagic rod, Healing Domain’s Healer’s Blessing, Loremaster feat requirements, Magician’s Metamagic Mastery, the feats for Heightened Spell, Reach Spell, Spell perfection and Preferred Spell, the Sorceror’s Arcane Bloodline and the Wizard’s Universalist School.
We also get 5 new feats to be used with this system as well as two new traits.

Conclusion:
This file has been exceedingly hard for me to rate due to several reasons. First of all, I don’t like the standard metamagic system, as it rarely gets used by players and is rather cumbersome. I’m also a fan of magic that may take a toll on one’s body, as reflected in years of house-ruling battlemagic and the like. However, somehow this pdf did not make me jump up and scream “Yes, that’s it!” I was thinking quite hard why that was the case and found the answers: The first one being that, while taking many special metamagic-using abilities into account, it does not provide guidelines for future additions. The second would be that, while comprehensive and well-written, it is not as comprehensive and well-written as some other releases by Spes Magna Games: It took me 3 pages to get the general idea of the system and while the presentation is concise, I think showing the table with all the modifiers before explaining the basic premise of the system is a needlessly complicated way to lead one into the new system.
That being said, you do get a, at least in my opinion, better metamagic system than the one in the standard rules for less than a bus fare.
Another major plus is the excessive support of the APG.

In the end, I’ll settle for a solid 4 stars for anyone who is interested. For all the people who abhor the current metamagic spellcasting system, but want to keep most of the rules intact, check this out – for you, this is a 5 star-file.

Ars Metamagic by Spes Magna Games

This product is 13 pages long. Cover, ToC and introduction take up (3 pages)

Next it jumps into the meta magic abilities for casters. These are the existing meta magic feats tweaked a bit. Now instead of taking the feat and then using a higher level slot. The caster cast the spell and must make a DC check. If she makes the DC she cast the spell with the meta magic added on. Failing causes feedback, anything from the spell working but lose of meta magic points, to con damage, to con damage and being fatigued. A caster is limited in the number of meta magic abilities they can apply per day. (4 pages)

Next it goes into a section on how to use the rules in your game. It also gets into what would need to be changed about some of the existing rules, such as arcane bloodline sorcerer etc. It explains how the changes that would need to be made to use these new rules. (3 pages)

The next section has new feats, traits and a new meta magic rod magic item. (2 pages)
New Feats
Extra Metamagic Art
Extra Palette Slots
Greater Metamagic Art Focus
Metamagic Art Focus
Resist Magical Feedback

New Traits
Metamagic Talent
Palette Variety

It closes with a OGL.

Closing thoughts: This is a interesting book with a new take on how to apply metamagic to spells. It has a bit of a risk vs reward. I really like the direction and flavor of the product. It makes casters a bit more into what I would like them to be. Though I would have liked to have seen casters able to do meta magic more with even more risks involved but it is a nice first step in my opinion. The writing is good and pretty easy to understand. The layout is ok. The artwork what there is of it, is meh. For the price I recommend the product if the topic interest you in the slightest. I am giving this a 4 star, the price helps make up for the few short comings.