My bike was stolen

and I've been keeping an eye out for a replacement... I found this really nice fixie:
The colour makes we want to run away and hide so I'll add a few cans of black paint to the price, but it's listed as $300/negotiable and I think it could be really sweet to ride. What do you guys think?
I've never ridden a Fixie before but I'm fairly fit and not really in a hurry to get to work each day. My only worry is my commute includes is a 5% climb that takes me about 5 minutes to ride up (on my Giant CRX City that was stolen). I usually use mid to low gears on the climb but I think I could easily do it with higher gears, and I don't really mind walking up the last bit for a few weeks if I need to build my fitness level up.
Should I give it a try? If I decide it was a mistake, is it a difficult conversion to add in-hub gears, or will I have to sell the bike?
Obviously I'll have to ride it before I buy. The seller only lives a few blocks away from me.