If you plan to get out right after your commitment, then no, definitely wouldn't take the bonus, it's also risky for someone without prior military experience as you might end up really hating the military, and staying in an extra year could be quite awful; one caveat, if you planned to take out any loans at all to supplement your stipend during school (or buy a car or something), I'd consider the bonus as an alternative.
Personally I took the bonus, but I plan to finish my 20 years in the military, so it's a no-brainer for me.