For anyone who as just started playing, the DLC (updates, more accurately) items Sega have been adding are worth picking up (and you'll want to go to the shrine for upgrades anyway). The last lot included the Marlin Cannon (which is a cannon shaped like a marlin, go figure) and a diamond plate which sells for ¥100,000,000. Not a bad leg up at the start of the game!

Is there anything worth checking out if you have already finished the game? Marlin cannon sounds cool, but I might just look up a youtube video of it.

@odinsmana: They haven't added any content that would give you new things to do. It mostly seems tailored toward making adventure mode more enjoyable. Costumes, weapons, money.

@veektarius: OK, thanks!

Yeah selling plates and stuff make the early going more pleasant for sure, but don't feel cheap at all really. For me it just let me grab some high level abilities pretty early on.