It's a high quality lens and not too expensive (compared to many other longer lenses) which makes it a very popular choice for many. The light issue after the sun goes down is going to be a problem though. In an ideal world you'd want a 5DMIII (For both the high ISO capabilities and the fast AF) combined with a 300mm or 400mm f2.8 lens. Those are sadly not cheap options and shooting low light long distance action photography is, sadly, one of the areas where you can't easily skimp on the costs.
The only other option you might consider is a used Sigma 120-300mm f2.8. Whilst you lose the IS of the 300mm f4 and the zoom is heavier, you will gain an extra stop of light to work with. Handholding at 300mm shouldn't be too much of a problem since you'll need 1/300sec or faster at least to get clear action photos. That will push the budget up sadly, if you want improved performance over that the sigma 120-300mm f2.8 OS would be the next setup up - most certainly not cheap, but giving you better performance and the OS (like IS).
After that you're onto second hand Canon 300mm f2.8 IS L or the amazingly expensive 300mm f2.8 IS L MII.
Consider how your finances are now and how they will gain - saving for the top end gear is a worthy goal, but you've also got to consider your shorter term goals as well. No point waiting years to save for a lens and not being able to shoot what you need to.