Quite frankly it depends on the person, everyone reacts differently because...well, no one person is the same (duh)
Alot of the problems I have today are a result of my eating gluten for 19 years. I'll just list off the things I attribute to this: asthma, allergies, really red face when I work out and an extremely high heart rate while working out (like...way too high), spider veins and vericose veins (at age 14 I shouldn't have to feel embarrassed when girls make comments about the "purple things" on my legs), and red bumps on the back of my arms and tops of my thighs. These are all things that I am highly self conscious of, even now.
When I eat gluten now, whether purposefully (that Pazookie at BJ's was far too tempting...a giant chocolate chip cookie all warm and gooey covered with vanilla ice cream!?! mmmm) or accidently (Caesar dressing...) I react in a few different ways. Either my asthma and allergies kick into full gear, so i'm gasping for breath in between each spine breaking sneeze and watery eyes, or I have, shall we say, indigestion. My thoughts get cloudy and fuzzy and I just feel awful in general. All that is only what I NOTICE happening. Inside something entirely different is going on. The gluten i've eaten is causing an all out civil war of sorts in my body. My body doesn't recognize the gluten protein as something good, and since the gluten attaches itself to my Villi inside my intestines my white blood cells begin to destroy those Villi.

Why do I need these Villi? What do they do for me? They are little hair like receptors that absorb the nutrients in the food we eat. So when the Villi are gone, I can't absorb the nutrients I need. As a result those senstive to gluten/celiacs often are malnurished and have deficencies.
OK, so what happens to me when I eat gluten isn't all that bad, thank GOD. Some people get terrible diarrhea, weight loss, inability to lose/gain weight, allergice reactions, mild weakness, bloating, bone pain, etc. These are just the immediate results that can happen.
Celiac and Gluten-intolerance is a LATENT genetic disorder. I'll talk more about the long term affects. This post is getting far too long.
--------------------------------------------
--------------------------------------------
Today's Plate!
Breakfast: Apple Raisen Walnut Granola made by Bakery on Main mixed with Craisens and Apple Cinnamon cheerio-type cerealGlutino brand(all gluten-free of course) and Tazo Chai Tea.
Lunch: Mexican Rice and Earl Grey Tea. [[granola is filling]]
Dinner: Grilled chicken on a bed of spinach with red and yellow bell peppers, mushrooms, and carrots with a drizzle of balsamic vinegarette and olive oil.
-------------------------------------------
-------------------------------------------

Think of all the chocolate that doesn't have gluten in it.