Despite the above, it's worth a try. First, you don't have to concentrate on the words. You'll have looked up the plot beforehand, and have possibly bought a programme. There are surtitles - yes, just like in pantomime - so you know what they're singing about, and you can just enjoy the tunes. (Never, ever, go to watch an opera in English unless it was written in English.)
Second, the voice of a trained opera singer is truly astonishing. Unlike musicals, there is no need for microphones
Third, the spectacle can be breathtaking. No longer are you expected to dress up; wear what you like. There are 40 to 60 musicians in the orchestra pit, and soon enough they strike up the overture. If it happens to be something special such as The Marriage of Figaro, you'll be bowled over before you even hear those wonderful voices, see the colourful costumes and experience the special magic that opera brings.
Last, the price of admittance, thanks to subsidies, is surprisingly reasonable. I once took my wife to an opera with a cast of over 100 at the Albert Hall. We had the best seats in the place. The following year we went to see a famous comedian in the provinces and paid 50% more.
So, if you're new to this, which ones should you start with? Americans like Madama Butterfly because it's got an American in it, but to be honest, apart from a couple of seriously good tunes, there's a lot of shouting. Carmen is an obvious contestant: great tunes, splendour, and a good old-fashioned story line. Aida, as mentioned, is another mighty work, or if you prefer something lighter (and shorter) try Cosi Fan Tutte. If you're happy to go straight in at the deep end, the dramatic tragedy of Tosca could fit the bill. Go, then, and give opera a try; you'll enjoy it.