Will it be useful enough ??Is there something better ??

It was useful enought for me, I used it to debug my bootloader for the Accelent IDP (which is based on armboot, an ancient release of u-boot).

I did not use the thingy to debug Linux itself. There was no need, althought the device would be useful.

However, I use it all the time to flash my eeproms.

And I wrote gdb scripts which test various hardware devices, without any bootloader or linux running on the target. That's quite nice.

I don't know if there is something better.