* The maximum amount you can pay in a certain route is determined by the guy with the LEAST amount of money in his channel
* Users can defraud each other in a channel, so they have to continually check if somebody is defrauding them.
* Unless you have a direct channel to your target, there is NO guarantee AT ALL that you can pay the person you want to pay.
* Users need to be online 24/7 if they want to be part of a payment route. If a user is offline, this particular route is not possible which of course has huge impact on the possible routes.
* Insane amounts of data are being sent because the network needs to be aware of EVERYBODY's payment channel's state (otherwise it can't discover a route)
* You still have huge fees if you want to wire money into/outside the channel.
* It's not feasible at all for bigger payments. Let's say you have to pay $1500 rent/month, are you going to open a payment channel and deposit 3 years rent in it ? Most people have difficulties enough coughing up the next month. But if you have to wire every payment into the channel, then you could just as well pay on-chain because you're paying that exact same on-chain fee.
* It's also not feasible for very small payments/channels. If you open a $30 channel with your coffeeshop to buy a few cups of coffee per week, then the price of your coffee doubles because of the huge fees to open/close the channel. Your only option is to route and HOPE there IS a route.
* Who is going to lock up his money in several channels anyway ? Liquidity, needed for routing money, is going to be a problem
* Very difficult to use and explain to users. No way your mother let alone grandmother is going to understand all this.