The initial thing which I noticed about the Caffeine shampoo was the smell. It has the typical 'clean man' smell to it, which isn't girly but I quite like the scent. The actual liquid is bright blue in colour, and has the same look to it as any normal woman's shampoo.
You use it like a regular shampoo- massaging it into wet hair and leaving for two minutes for the caffeine to do it's thing. When I apply it I properly massage it in, promoting blood flow to my scalp which is also meant to be beneficial to hair growth. I leave it for two minutes, you can feel a slight cooling/tingling sensation here as the caffeine gets to work and supposedly "travels along the hair shaft directly into the hair folicles" and, if left long enough "into the scalp".
It doesn't leave any residue at all in my hair and doesn't leave it feeling heavy or weighed down at all which is something that I was initially concerned about. It doesn't have any volumising/conditioning/split end protection etc. properties to it, so you will need to follow up using it with any conditioners, hair masks and oils which you normally use. The Alpecin Caffeine Shampoo doesn't leave my hair feeling dry at all so you probably won't need to use any extra products than you normally use to nourish and style it.
I don't really think I have any bad points to say about this shampoo. I do however not have colour treated hair and I use very minimal heat on it so I'm assuming results may vary if you do either of these on a regular basis.
I've been using it for over a month now and during that time I've had several people commenting on the fact that my hair looks longer and I've also noticed myself that it does look longer and healthier than before. It retails for around £5 in Boots, so it is definitely worth picking up and trying if it is something that intrigues you and feel would work for you.