For me not worth to use it having extremely good tools like the offering from WISO.
In my opinion a complicated tax law is a direct attack from the State against low and middle income population. If you have low income and poor education you will not be able to make use of the tax law to increase your available income, something that high income citizens do daily.
In this case we have to thank the free market to provide really easy tools for less than €30 so middle and low income citizens can start at least to take advantage of the tax law.
I’ve lived in multiple countries and always did my tax report myself. And the German situation is so blatantly designed, compared to other countries, to benefit only a very small portion of the population.
Not only that, If the amount of man/hours that the whole country of Germany spends doing taxes would be spent on productivity gains or just normal work, the country would become immediately the richest country in the world. Instead, it’s just wasted effort and work.
"extremely complicated to use" well, that is something that you hear often from Tax advisors or tools for less than €30. Same FUD tactics.
In France you have to declare taxes, but everything known to the tax authorities is pre-filled, leaving you to add any special incomes/deductions that didn't come trough regular channels that get automatically reported.
You still have tax consultants to help you optimise if there are higher revenues, but it's a very niche service.
In Germany tax-prep industry is huge, there is a huge network of tax consultants plus paid online services like taxfix and smartsteuer.
The only countries I lived which didn't require you to declare the taxes were Russia and Georgia, mostly because 13% and 20% flat tax rate respectively.
Any country which does have complicated progressive tax system would require you to declare taxes at least at some cases.