I've been a governor for 6 years, and I enjoy it. The time committment is not that great - 1 FGB every term, plus one or two committee meetings each term, depending on what committees you attend.
I think its important that you DONT go into it thinking you are there as an operational manager. You are not - thats what they pay the head teacher to do. You are not there to critique lessons or change the curriculum or dictate the pay scales or follow your own agenda - its a big mistake to think that, although we have seen many parents come and go waving their placard for school lunchbox policy or homework policy, only to never come back once their rant has been heard.
You do not have power per se - you are not trained to be doing that. You are there to provide a neutral look at whats going on, and to challenge what you see, to ensure the best outcomes for the kids.
In the time I have been a governor, we have changed very little in the school through direct intervention, but we have monitored what is happening and highlighted concerns that have gone on to be part of the schools strategic plan (girls attainment in science was a biggie, and the school now have a huge review going on with science curriculum, plus the PSED of girls and risk taking behaviours and independence).
Strategically we help the school focus on areas for improvement - not in teaching - that is the heads job - but we do have a say in the softer areas of childhood development and how we want the school to use its resources. WHere we see anomalies in attainment, we do challenge and require the head to either explain or plan interventions to bring children up to standard.
As a consequence, our school has a great reputation for early and effective intervention - on the negative side, it does make us look like a SEN school, with over 30% of kids on the SEN register.
Once you have been a governor for a while, you will find that the GB follows many of the recommendations of the head - mainly as these ARE the strategic priorities, and while it may feel that you are rubber stamping, it is more that you are in violent agreement about what needs to happen.
As the GB becomes more open and strategic in nature, we have found that the head is more open and trusting, and so we do get more information than when there was an antagonistic approach.
I think if its something you stick with, it becomes more rewarding. If you only do it for a year, I can see how you would feel powerless.