I think they are a great way to protect your hair...in fact, I may be getting more soon!!
But you know what, in reference to your last post, I saw the cutest wig on this poster outside of the beauty supply store. I really think I'm going to go back and try it on...and I'm 18, so don't let age keep you from a cute protective style...
I have them in right now and I wash just about every week. I use diluted shampoo and wash in 1/4's in the sink. (it's nasty how dirty the water gets sometimes. My only issue with any kind of extentions is conditioning! I Use the braidspay/infusium mix for my own "hair" throughout the week. My hair grew nicely with my last twist, but since I discovered this site a week after I got them done last time I might have to take them out early. They've been in for about 5 weeks and my newgrowth is RIDICULOUS. I have been using MN/ Fake MTG usually I might have 1/2 inch by now. NOw I have about 1 1/4!
They can be washed.
I've had my hair in twists on and off for 6 months. I currently have 3 inches on NG (0.5 inch per month) and took them out only 2 days ago.
I have pics in my fotki, from when I did them myself. The pic in my siggy is on my twists. Den1's album is worth checking out. She has a step by step tutorial for washing with braids in.
I always see growth when I'm braided. It's retaining the length that's the tricky part. Keeping your braids moisturized, clean, and conditioned is essential.