I've found 3 datacrons so far. Two gave me a stat boost and third gave me a Blue Matrix Shard. Now I have a couple questions:
- Is there anything else I can get from datacrons?
- Where are they all? I don't want to miss one.
If you want to make sure you got all the datacrons on a specific planet, look at the Codex entry for that planet and then click on the magnifying glass. It shows your progress on that planet, including how many of the datacrons you have:
As for the rewards from datacrons, it seems it's only stats boosts and matrix shards, but I can't say that for certain.
Balmorra (Empire) datacrons
Balmorra (Republic) datacrons
Dromund Kaas datacrons
Nar Shaddaa datacrons
Ord Mantell datacrons
About every 1 in 3 (or 5 in the larger planets) instead give you a Matrix Shard of one of four colors: red, blue, green, and yellow. These shards can be combined, and depending on the color order and choices, different permanent stat boosts can be created in the capital city of your respective Side. See How do Matrix Shards work and where can I find them? for more info.
See other resources on the 'net for the lists if you want spoilers. The best list I've seen is at swtor-leveling.guide.net DataCrons, Matrix Crystals, Relics Guide, but it is based on preview/pre-release locations and I know some have changed already. Also, try Republic Trooper's Datacron Locations & How To Get Them.
My favorite is Torhead's Codex Datacrons list. Though it might not be the best list format, once you pick a datacron based on its codex entry, then this site has the best comments, screenshots, and videos to help you find that datacron. Especially considering many require travel starting from a certain point, making the final datacron coordinates (which most lists list) fairly useless.
Of what I've experienced, datacrons can be found around the world at fixed locations. They give some permanent stat boosts, as I heard.