The smaller the Zepp, the better the side seats are. Even the furthest side seats/obscured view seats in the front are often still right in front of the stage with minimal obstruction. (ie: Sapporo)
The arena is FLAT. There is no slant (though some do have steps up between areas which may be nice if you’re in the front row of your area. See each individual page for more details).
Balcony seats are by no means bad, but feel free to bring along the opera glasses if you know you’re going to be locked-on to your oshi the entire time. Depending on your height/preferred perspective, balcony seats might be better than the back of the arena floor.
If you suspect you’re going to get a standing ticket during day-of sale, consider shoes with chunky soles to give you that height boost, as standing tickets have no height advantage against the seats directly in front of them and it can become rather hard to see, even if you’re already tall.
(Personal story: I am 177cm and won a standing ticket for the very last row up in the balcony at Zepp Osaka Bayside, and found myself on tiptoe for most of it trying to see around people’s heads from the last row of the balcony seats.)
(The potential inverse of this: if you don’t get a standing seat in the back and find yourself in the middle of the crowd, come prepared with the resolve to crouch a bit the entire time…)
Capacity may be slightly reduced during streaming days, though I don’t believe it’s to the same extent as Stellar Ball (which loses a solid 60+ seats from an already small venue).
Zepp Venues charge an ADDITIONAL AT-DOOR DRINK FEE OF 600 YEN that is separate from the ticket price. There is no option not to pay this and payment methods may vary by venue. You’ll be given a token to exchange at the counter, generally immediately at the lobby when you enter. Drinks are all bottled (water, tea, juice, sports drinks).