Please note it is possible to found it with 12500€ and have to provide the other half of the 25k€ later.
My first company was without the GmbH protection and benefits. It was ok but I would not do or suggest it to anyone. Hell of a pain to migrate to a GmbH later.
Given that the 1€ founding is an illusion anyway, as you will need to have some money in the company to pay your accountant, Berufsgenossenschaft, (the salary you are living off if you are working full-time), etc., the benefits of requiring somewhat less (maybe 5k instead of 12.5k) are not that great.
Beside that, UG has very bad reputation and if you need something your company rating will lead to problems like prepayment when ordering goods. New GmbH is not the best either but increased quite fast.
In addition, transition from UG to GmbH is a bit of a pain, as you need a let your books be checked (costly) or by just paying the amount to reach the GmbH money.
I’ve read that the “most straightfoward way” is to create a new GmbH and transfer all the IP away from the Einzelunternehmen. It seemed kinda complicated though. (As everything is when dealing with the Finanzamt IMO)