First go with new 18.5 WSM

I just wanted to say hey and let everyone know that I smoked my first slab of pork back ribs today om new WSM. Actually fisrt time ever using a smoker at all. Great experience and I could not believe how good that meat came out. My wife and I were truly amazed and according to all I read before trying this smoking thing out, I didn't even do it right. I had trouble with keep the temp down. 275 was about as low as I could as I could go and still came out with an outstanding dinner. Soon as I get the temp under control id like to smoke a brisket.

Well done!
Don't worry too much about keeping the temperature. You need to use the wsm a handful of times before it seals properly and before you get the hang of it.
Using it for pork, chicken, fatties, meat loaf, and even beef short ribs etc is a good way to start off

And Show us some pictures

275 is a good temp for cooking ribs

275 is ok. It just shortens the time a bit but they still turn out perfect

Welcome to the forum and thanks for posting. I hate to disagree with a newcomer but it sounds like you did everything right. Fired up the WSM, cooked delicious ribs, and made your wife happy. That's a good day in my book every time. You'll find that while it's nice to hit a target temp for the whole cook being off some doesn't ruin the cook. The goal is good tasting food and you're off to a great start. There are several factors that will give you higher temps than you're shooting for. If you use the Minion Method with your coals you only need 10 to 15 lit coals to slowly reach 225° in the cooker during the summer and the temp will rise slowly so that you can catch it on the way up by closing some lower vents. I give myself an hour to light the coals and get the WSM up to temp. You'll figure out what works for you so enjoy the ride. .