Just finished the story mode and I have to say it was very enjoyable, and worthy of the asking price.
Ironically playing First Light served to highlight most of Second Son's many shortcomings. After using Fetch it became increasingly obvious that Sucker Punch's decision to make Delsin the "jack of all trades" to the point of him feeling weak and diluted, was a misstep. While Delsin's skill set felt disjointed, Fetch ended up being infinitely more satisfying to play. Her powers were more fleshed out, packed more punch and her means of traversal made movement feel seamless. Compared to Second Son's movement philosophy of press circle to win, this was far more engaging. The improved traversal mechanic also meant that Lumens (the equivalent of shards) were more enjoyable to collect as there was a better balance of skill and tedium to their placement. If you were skilled enough, most of them could be obtained without breaking stride while simply moving to your next objective.
The fact that you were restricted to a single district with a condensed storyline actually worked in First Light's favour. Every district bar Chinatown looked virtually identical which made them feel largely like a waste of time. Unfortunately the mission design was basically identical to Second Son's, albeit with a few minor tweaks. Despite the combat scenarios hardly being any better than the base game, they were still more enjoyable. You actually felt like a superhero in First Light, with slick movement, more efficient ways to manipulate the environment and simply more firepower (Sucker Punch clearly knew it as well, which is why they included Arena Mode). Again, with the condensed game length they pretty much wrapped up just when they started to get stale. Still, this is one of the AAA games that I feel could do with more set pieces just to mitigate the monotony to an extent. Sucker Punch kind of lost me with their efforts though - you know it's a problem when story line missions feel practically the same as random fights in the open world.
Anyone who read the Second Son OT probably remembers my incessant whining about the audio mix and sadly, it's not much better here. I will say that Fetch's Neon powers sound like they have more oomph to them, which probably aided in making her feel more powerful and satisfying to play compared to Delsin. The ambience is still non-existent unless you turn your volume up to obscene levels. By now I've basically lost all faith in Sucker Punch ever getting the audio right their games.
Overall I really liked it, and there's very little chance anyone who likes the base game wouldn't. This DLC basically makes Second Son obsolete if you've already completed it, as if I ever need my Infamous fix I'll definitely go to First Light. It's also a very good purchase for those people who were interested in the original game but didn't want to commit to paying $40+. It's the best of Second Son in a neat little package, so you really can't go wrong.