Marie Lu has a really appealing writing style. Honestly, she does. Legend ran as smoothly as Warcross, although it's probably for a younger audience.
I've had Legend in TBR for many years now, but I only just had the desire to read it now that the last book is out. My reading tastes have been going through a sort of metamorphosis of late, with an increasing aversion for unfinished series. Then I've been gravitating toward more YA than the regular Epic, but it's all good. At least I'm reading.
Legend is what you get when you cross Red Rising with Hunger Games. There's nothing new, I found, particularly after having read the two previously mentioned series. The tropes and themes are more or less the same: a post-apocalyptic America, a corrupt government, a filtering system to weed out the weak, two young, daring protagonists... We're also beginning to see the hints of a possible love triangle. With the bad blood already in Legend, it would be interesting to see how it develops further in the next book.
The world of Legend is quite well done. Nothing unnecessarily elaborate, enough focus on events and main characters, the number of the latter being perfect for such a small book. It's easier to start with a few characters and loads of potential twists and cliffhangers than tangling everything up with multiple characters, which is one of the reasons this is an easy read.
Marie Lu's Legend is promising stuff!