i took 3 months off at the end of 2010 because my partner was on sabattical in the states and i wanted to travel with her (and can't work their due to visa issues). it was great not working (or more exactly, being able to choose what i did), but i don't think i learnt much more than i would have in, say, 6-9 months of doing stuff on an evening and at weekends. the biggest win was that it brought us closer together (another bonus, more particular to my case, was that living in the usa gave me access to new egg, amazon and adlibris, so i read a pile and built a new machine - mini-itx based - that came back as hand luggage) .
financially i didn't have any worries - i had a pile of savings, a job to return to, and my partner earns enough for us to survive on anyway. one thing i would suggest is talking to your employer about it - while they may be unhappy to have you take time off, it is also likely in their interest to take you back afterwards (assuming you're a decent programmer, which i would guess is the case if you care about learning) (although a year ago the economy was heading down, so it made more sense to give me a break then).
financially i didn't have any worries - i had a pile of savings, a job to return to, and my partner earns enough for us to survive on anyway. one thing i would suggest is talking to your employer about it - while they may be unhappy to have you take time off, it is also likely in their interest to take you back afterwards (assuming you're a decent programmer, which i would guess is the case if you care about learning) (although a year ago the economy was heading down, so it made more sense to give me a break then).