I used a doula and I loved it! They really help to coach you through the process.

I think it really depends on your personality.  I personally didn't want anyone there except my husband, especially someone I didn't know.  That being said, I think it's awesome for those that are comfortable with it.  You'll have an advocate there to make sure the birth goes as closely to your plan as possible.  You might bring in your own birth plan but that doesn't mean it will get followed and if you don't have someone to speak up for you while you are in labor you might end up very disappointed. Try interviewing a couple of doulas and see if it feels right to you!

I never used a doula and had all 5 with no epidural.  With one of them I had a mid wife and it was wonderful.  She was with me all the time and even sat in the shower with me holding the jet to my back and monitoring while in the shower.  I would have done the same with my last two, but we moved and their weren't midwives that worked in hospitals nearby.

I think you should research it and perhaps meet with one or talk with some others who used one. I had all 5 kids with no epidural and no doula. I did go to Lamaze classes with my first but I had great nurses and a wonderful doctor. It is a very personal choice.

Check out this video

Why not? Doula's are very helpful. When my wife was pregnant we looked for a North York doula near me and it helped us with the journey.