A Cool character, but poor value proposition.
The Mass Effect franchise has always had a spotty relationship with DLC purchases. On the one hand, pieces such as the Overlord or Shadow Broker packs from Mass Effect 2 were great value: pieces that expertly combined combat and storytelling; advancing the franchise in new, revelatory ways. On the other hand, there were pieces like Pinnacle Station and Arrival; short, uninteresting chunks of gameplay that focus on the worst parts of Mass Effect and barely advance the plot.
In a way, From Ashes fits directly in-between both. A remarkably short piece of content, From Ashes leads Shepard to answer a distress beacon from Eden Prime, the first human colony off Earth. Prime, which has been attacked by Cerberus troops, serves as little more than an extra N7 mission that sees Shepard kill a whole bunch of troopers, press three buttons and open a stasis chamber containing nothing less than a living, breathing Prothean, Javik.
Javik provides Shepard with visions of the fall of the Protheans, akin to when he was first touched by the beacon on Eden Prime, as well as filling in the truths of the Prothean race and their encounters with the Reapers. I won't spoil anything as fans of the series should really see this information first-hand (or seek it on YouTube), but it is enlightening to say the least. It will make you reassess the information presented on the Prothean race since Mass Effect in some fairly key ways.
Javik is an able party member,using some unique combat and biotic powers. Unlike previous DLC characters from Mass Effect 2, though, Javik's dialogue does not seem patched on after the fact - his dialogue is unique and context sensitive, with crew members adressing him directly. He is a fully formed character and integrates well into the crew.
My problem with From Ashes is that it seems like poor value for new customers. 800 Points for one N7 mission and a character, no matter how revelatory he may be, seems like a tall order. I just don't think that the value proposition makes sense. at 400 points, sure, but 800 is too much to ask. If you've already got a code with your edition of the game, it's worthwhile content. If you don't, maybe look up the information elsewhere - it's not worth that much of your money.