Since there are many contributions to the topic of /e/ here, but there is apparently none that deals with the topics that are perhaps not quite so euphoric. The bad sides, which should also illuminate.
Therefore following my absolutely subjective impression and my experience with /e/.
On the one hand that there is no root out of the box and this feature is not wanted, as well as discussions about it in their forums, apparently not directly forbidden, but nevertheless unwanted.
On the other hand that you must believe the promise of privacy, because there is no possibility to check it.
The handling of bugs in their system, when you open a bug it takes days until the developers register it and you get a response, even if the bug has a security tag.
For example, currently it is not possible to connect to a wifi which protects its managmet frame.
You could also say directly that it does not comply with IEEE standards, more precisely IEEE 802.11w-2009.
This unfortunately has the consequence that in places where a higher standard of security is required than usual, you can not connect to the wifi. Especially the violation or not implementing of security standards leaves a really bad feeling, which is only topped by the performance of the responsible developers.
Moreover, /e/ has appropriated the work of LineageOS without giving anything back to this community,another point that leaves a really bad impression.
These are only the points I noticed, of course the data transfer to google is apparently prevented, but all in all I cannot recommend /e/ to people who like to have control over their own device and want to understand what is happening how and why.