I've been taking singing lessons for about a year. The latest marvellous discovery is that if you have proper breath support then you have a whole lot more time & space to pay attention to delivery as you're singing. Its a small point, but makes a huge difference to what you can conciously communicate.
Actually - there's tons of marvellous discoveries to be made - its definitely well worth getting decent lessons.
My teacher does not like folk music (she claims its too miserable - I think she hasn't been listening to the right songs....), but she respects the fact that folk is what I do. So she has been teaching via show tunes up to now, and we are about to move into classical. This hasn't made me sing folk songs in a show tune style - its a case of taking across the useful tools from the one idiom to the other. I've got the same amount of passion & soul as I ever had - the difference is that with a bit of training I can communicate that passion & soul much better.
The only down side I can see is that training has made me more likely to focus on the flaws in (mine & others') singing technique - which can be a bit distracting - so it has changed my listening tastes a bit. Anyone else find that happens?

kris