DOJ's main attraction is the game's basic feeling, something about the way bullets and the player ship move feels better than other games, even Ketsui which was a year later on the same hardware feels slightly off in comparison to DOJ, not that I don't love it for other reasons.
Feelwise it still irritates me by having some way too big bullets with a pixel sized hitbox, wouldn't be a problem but whenever games do that they also eventually make you hug those bullets down to the hitbox to survive smaller bullets charging at you while your instincts are screaming at you not to do it, the big bullets never really helped me visibility wise.
Blue skies debate aside, DOJ is about the last time you had really super detailed backgrounds with CAVE I think, Ketsui right after still had really nice ones with some better colors but still dropped a lot of detail and had an even more prerendered look, later than that you get tons of looping the same scenery and none of the same insane detail in individual setpieces
http://shmuplations.com/wp-content/uplo ... tsui01.jpg vague comparison of doj and ketsui st1 and their level of prerendered-ness
https://www.youtube.com/watch?v=6vNuz4OEDJk#t=13m15s some parts in doj where the detail is through the roof are the aftermaths of blowing up the giant cannons in st4, but there's many others
About drawbacks like getting walled-in and strict chaining, those are kind of DDP staples and they feel easier to deal with in DOJ without being too easy either, kind of in the right place.
I really find chaining to be a lot easier than in the original DDP, I mean, why do hypers even exist? They're both a panic button and a "auto-chain for a while" button if you make an effort to wiggle around. And trying to escape walling-in is a lot easier if you have a smaller hitbox, you can bs your way out there.
The chaining does feel cool if you can do it (I can do stage 1 at least) but it suffers a lot from being a typical enemy chaining system with a really small timer and few special setups/enemies, your "crucial chain-keeping targets" end up being hidden in a huge sea of identical enemies and this makes it really hard to remember what you're supposed to shoot and when as there's nothing remarkable from enemy to enemy, a chaining system like in Ikaruga or Bakraid that's based around special enemies that stand out and setpieces is a lot superior, at least as far as helping you remember what you're supposed to be doing.
Lastly, the references to Ikaruga in DOJ are really cool, so that always adds a little bit to my enjoyment in playing this game.