As mentioned by others, clearly a Green Lantern inspired mage concept. It's a very accessible idea, and could easily fit into nearly any campaign. In my mind, it's something more likely to be taken for NPCs. It adds some offensive capabilities to a spellcaster - such as emerald armor, weapons, and some save bonuses - at the expense of spellcasting advancement (gaining a spell caster level once every four levels). I'm left with the feeling that the result is slightly underpowered.
The writing and grammar weren't, um, strong, but didn't outright offend me. The single piece of art was nice, and the product was well laid out. Potential buyers should be aware that only 3 of the 6 pages are game content. One page is an ad/checklist for the series, and the other two are the OGL (the OGL traditionally takes one page in products like these. Here, it spill over by a paragraph or two.).
Despite my reservations, I wouldn't be opposed to using this class in a campaign as NPCs. For the price, it was worth a read.
[3 of 5 Stars!]