If you do not use a printer, yes, it is safe, generally, to have the Print Spooler service disabled... with one issue:
If you use applications that use the subsystem of the printing aspect, you still need Print Spooler. The Fax service also comes to mind.
An example of this would be certain document "converters" of sorts that pipe data through the printing system to get a different output. One that I have come across is certain document to PDF converters. If this is not a problem, then, generally, yeah, it can be disabled. Just be aware that down the road, this could become an issue.