I think an integrated battery looks better, but there's too many drawbacks, from battery range to having to charge on-bike, especially for apartment/condo dwellers.
On-bike-only charging can be a deal breaker, whether they have to store their bike on a balcony, or in a shared space.
This is especially true in climates that see regular temps drop below 10ish degrees Celsius, given the nature of lithium batteries.
This was on the shortlist be my 2nd e-bike...
The most Stealthy bike on the market, with a hidden battery and discreet mid drive motor... this bike looks like an ordinary road bike but packs a big punch.
lunacycle.com
...except for the small, internal battery. I'd love an easier way to pop it out, both for charging, and for being able to buy multiple spares to optionally go on longer rides.