i know a few people who have a bike as sole form of transportaion, and ive done it a few weeks at a time.
in the winter, it depends on how far you have to go. when it is low 30's outside, i have on 2 shirts, 2 sweatshirts, and a mesh jacket with a winter lining. and i would be frozen 3 minutes down the road. your hands freeze and you cant feel them. but if your ride is 20 mins or less, u should be fine. i hateit cause i was riding 50mins at 6am at 60+ mph.. so it was cooooolllld.
rain: there are cheap rainsuits you can buy that will shield you from hte rain, but you will get a little wet. i rode in the rain yesterday and it wasnt bad.
i dont reccomend it. it gets old quick.
ill ride my bike to work and back all week, and then the next week ill take my car jsut cause i dont feel like riding. and for the fact that my car gets better mpg than my bike.. (88crx si vs 2003 zx6r with i/e / power commander tuned.)
but on the choice of 250r, they are great bikes, but i believe they are on backorder for a few months due to higher demand than anticipated.