I've been to Front Sight 5 or so times over the last 15 years. The curriculum has changed, but the instruction is very good. Regardless of your skill level when you enter the class, you will improve and leave better than you came.
I've taken the 4 day handgun class 3 or 4 times and the 2-day shotgun class once. Even repeating the handgun class, I pick up more and get better each time.
As far as the marketing goes, yes, they will bombard you with calls and emails. If you hear out one of the calls, there is an option at the end to opt out of future calls. I did this and never received another call.
You can also opt out of the emails, but that's really where you hear about the deals they offer. I'm now a member, and some of the member deals they offer are really good. Like $100 for a lifetime membership to go to FS as many times as you want and take any class they ever offer, for free. Several of us at work bought them and a few of us have been through the classes.
I believe it's well worth the money spent.