Task sequences are easy to create generally, but the results might not always meet expectations.
The best way to troubleshoot task sequence errors is to view the smsts.log or the task sequence log on the client. Although many lines of information are in these logs, it is usually possible to isolate the issue by searching this log.
If you added the command line option to the boot image, you can open the command window on the client by pressing F8. So long as the command window is open, you can view the logs or copy them to a USB key or network share for further analysis.
Also, when working on a problem, the Support organization will request these logs.