This is 3rd hand information from an account that I call on that has one on their (business) property:
It is a very lengthy contract, that basically has no premature out. Once they build it, they sure as shit aren't going to move it, so you need to be ok with it.
They will pay handsomely, but only to a certain point. Yours is likely not the only site they've considered and if you push too hard for more $ or whatever else, they can and will easily find someone else.
Once its in place, you will likely not see too much going on with it in terms of service calls, upgrades, etc. that would be cause for crews to be on your property. However, if and when they do need to get to it, because of FCC regulations and priority, they are going to be able to get to it at any time.
Additionally, there is a chance that the contract will require some greater right of way access that could include a significant portion of your property, again, on their terms.
The potential $ that you could bring in could be significant however. The fella that I'm speaking about brings in a sizable chunk of extra "income" simply by having it on his property. Something along the lines of it covering his mortgage and some of the associated utilities/bills. Also, it is at his business's shop, so he doesn't have to see it when he goes home at night.
That being said....
Even with the extra land that we have here, I sure wouldn't be comfortable giving up access rights to my property. Definitely speak with a lawyer AND a few real estate professionals. If you're ever planning on moving or selling your place, this could be a HUGE issue. Value, insurance, etc.