As with any drug / stimulant, it will tax your system. It might help or be fun, but the next day (or next few days / weeks) you'll have to pay the pied piper. 

Source: I used to smoke weed and drink lots of caffeine, and overall find I'm more productive if I cut out both. 

Don't get me wrong, weed can be lot's of fun, and every once in a while maybe isn't that bad (I recommend sativas and landraces, preferably landrace sativas, and know where your stuff comes from). 

As always, everyone is different, YMMV, etc. I found for me, I'm better off without it.