Well, like many other people I was a little nervous about cleaning the sensor myself but it was easy and successful. I had 2 small marks showing on pictures. I have a Nikon D7000. One application removed them and test shots of clear blue sky showed clear with no smudges.
The reason for 4 stars is that the instructions are rudimentary. However, if you go to the visible dust website they have detail and videos which are really helpful. It is a little tricky and you only need to touch the solution to each corner of the swab which then soaks up the small amount of the solution required and makes sure the swab is evenly soaked. Do not pour the solution on to the swab!
Key tip - make sure you thoroughly clean the mirror chamber before you use the mirror up facility to then expose the sensor. This helps avoid getting more muck on your sensor before and particularly after the clean.
Given that it worked I think the value is fine... it costs about £45 for one professional clean for example. Do not be tempted to reuse the swab. The solution is enough for 4 cleans.
This product with Vdust Plus solution says it will deal with aqueous and maybe slightly oily spots (Orange swabs). There is another version of this pack with Vdust Smear Away solution which says it will deal with oily spots (Green swabs). The Vdust site says first use the Vdust plus and then if that does not work use the Vdust Smear away. I did buy the smear away too but as the plus worked I have not used it.