My full review of this dripper is basically this- its horrible. It has multiple problems that are just really hard to fathom:
1) Brewing with a paper filter is just really difficult. It's hard to get the papers off the other papers(although def gets easier with practice) and REALLY difficult to pre-wet the filters. Even when you can get the papers wet without totally collapsing the walls, the flutes are not even close to clean looking.
This is a problem for all flat bed brewers, but the problem is magnified 10 fold with this brewer. At least part of the issue is caused by the # of flutes put on the filter. The paper and dripper, at least on some level, was designed to be proprietary for no reason really then to sell more filter paper. The dripper itself flares out at the top, again, for no discernible reason then to sell more proprietary papers.
This speaks to Damianwars issue big time, and great call out on it. We don't need more filter shapes. Make a new filter design that you think works well, sure, why not, but why fix what isn't broken(for the most part) unless you have a truly superior solution?
Here, we have an inferior solution that can't be fixed because Espro has decided that selling more sh**ty filters is more important then providing a quality solution for the consumer.
2) Having decided that, even though I NEVER brew with anything but paper filters, I'll give this a shot, I brewed without filters today. This is where an almost mind bogglingly awful flaw was shown.
This is a brewer designed for only coarse brewing(at least without a paper filter, which as mentioned above, is extremely poorly designed). The holes create a vacuum because coffee particles get stuck in it, causing extreme channeling. If you agitate(for this, stirring is needed) to let the water flow through all the holes, the water just IMMEDIATELY flows through.
In short, there is simply no way this brewer went through proper testing, and is a massive fail on what should be a really cool concept.