However, I will disagree... to a point. The Young Jedi Knights definitely COULD of been that, but those books were purely YA novel schlock. I say that as someone who was at the perfect age for that schlock to completely engross me into the EU for the next 6-7 years.
Oh, I never said they were
perfect introductions to the Solo Kids. Their charming little artifacts of the 90's, the same way that
Shadows of the Empire and
Dark Empire are. Certainly harboring more than a few narrative blemishes, some unimpressive prose, and humor and dialogue that reads more like
Saved by the Bell than Star Wars. Having said that, I feel like the books themselves are enhanced by all the places you see those characters go. I mentioned this in my Reading Guide for the EU, but some of the satisfaction of NJO and its sequels is seeing those same round-faced, starry-eyed kids like Jaina, Jacen, Tenel Ka and Zekk be subjected to the horrors of war, and rise to the occasion.
It doesn't make YJK uniquely good in a vacuum, but they become a staple of the Solo Kid's long journey...which is very similar to the role they play in Anderson's other work, the
Jedi Academy Trilogy. Weaksauce and sloppy book? Sure. But I'll be the first to admit that I loved all the scenes of Jaina and Jacen spending time with their uncle Luke as little kids, playing in the snow with 3PO, and using their favorite storybook to put on a brave face when they're both in danger. Little things like that make you grow attached to these characters, and watching their shift from kids to teenagers to adults, you almost feel like you're growing up with them.
I would even chock
Junior Jedi Knights in that same category, despite being even kiddier and schlockier than YJK, being the literal SW equivalent of
The Magic Treehouse: if for no other reason than seeing Anakin Solo and Tahiri Veila become friends for the very first time.
It was still YA schlock at the end of the day, and the Jacen of Young Jedi Knights and NJO are vastly different characters despite only year and half to two years of aging. YJK Jacen is who I kinda imprinted on as a child, and that's not the Jacen of NJO.
You are 100% right about NJO Jacen being a radical departure from his jokier, cornier YJK Counterpart. It's the one thing that NJO Purists refuse to acknowledge when they're lavishing the series in endless praise, and pretending that the "departures" to his character only came later with series like LOTF...when it already happened at the start of NJO. It's one of the elements about his character that is the most inconsistent, and went unexplained throughout the EU's remaining publication.
This is one of the reasons why I appreciate Troy Denning and Aaron Allston's attempts to bring back elements from YJK in their respective NJO and LOTF novels, making explicit references to Jacen and Jaina's adventures in those novels, and Denning even reuniting them with characters like Raynar and Zekk in
Star By Star, after being inexplicably absent for countless books. You could argue the efficiency in which they handled those characters and elements (Denning especially, given his weird fixation with shipping Jaina with Zekk at all costs), but it was appreciated regardless, and helped link NJO better with its predecessor...even if it was
really, REALLY late into the series.