The only time I've complained was when I had my daughter on my lap (she was 18 months and didn't have her own seat). It was already really tight and then the lady in front of me reclined. I didn't say anything to her until she kept turning around to give me dirty looks every time my daughter accidentally knocked her seat. Eventually I just said "What exactly do you expect when you recline your chair into a toddler?"
But usually I don't say anything. I think it's rude to recline, but it is an option, and a lot of people go by the theory that the person behind them can just recline too if they need more space.
I'd like to see the option taken away entirely. I've been on countless flights, several long-haul, and I've never reclined my seat.