The older Nordic SDK wasn't too bad (once you get over the learning curve). Trying to start a project from scratch is challenging though, so much easier to pick the closest example, get that going and modify from there.
However, they've deprecated the old SDK [0] in favour of Zephyr [1] and quite a number of people struggle with it (check the forums and general internet). I have less experience with Zephyr, but both of them use a lot of python support tools which seem to suffer from versioning amd compatibility problems (even trying to keep a stable platform has been difficult here, what works one time doesn't work a few months later). YMMV.
There are good reasons for depreciating the nrf5 sdk. However, I’m not sure how long the Nordic Semi lead is going to last.
Previously if there was a project that came up that didn’t strictly need BLE, I’d recommend the nrf5 sdk because it was reliable and stable. Now with the new sdk they are encouraging people to write firmware that’s much easier to port to other mcus (with zephyr) and the development experience has much higher cognitive load.
However, they've deprecated the old SDK [0] in favour of Zephyr [1] and quite a number of people struggle with it (check the forums and general internet). I have less experience with Zephyr, but both of them use a lot of python support tools which seem to suffer from versioning amd compatibility problems (even trying to keep a stable platform has been difficult here, what works one time doesn't work a few months later). YMMV.
[0] https://docs.nordicsemi.com/bundle/sdk_nrf5_v17.1.0/page/ind...
[1] https://www.zephyrproject.org/