Pumpkin is good, it is just a type of winter squash. It is good for more than desserts.
First, don't get a big carving pumpkin to eat, they are grown for size, not flavor. Look for a smaller pumpkin, or a "pie" pumpkin at the grocery store or farmer's market.
You cook it as you would any winter squash. You can cut it in half, scoop the seeds out, and put it face down in a shallow pan with about an inch or so of water in it, then cook on 350 degrees for about an hour. A simpler and more flavorful way is to wrap the whole thing in aluminum foil like a baked potato, and cook for 1.5 - 2 hours on 300-350 degrees. You'll know when it's done, it will smell cooked, and a knife inserted through the foil should go in easily. Take it out and just let it cool in the foil.
Then unwrap, cut the pumpkin and remove the seeds. Scrape the cooked pumpkin out of the tough outer skin and you're ready to go. Pumpkin can be used in soups and casseroles in place of any winter squash, or in place of sweet potatoes. The mashed pumpkin measures just like the canned pumpkin, just sub out the appropriate amount.