To start, outline your expectations and how your subject met them:  What did you
want? What did you get? 
Next,
outline the precise ways that your subject met or failed to meet expectations.
Use specifics and details:  explain exactly how your subject succeeded or
failed. 
You should have a good start with your details, so begin drafting the essay.  Name
your product/service in the first paragraph so your reader identifies the
subject.  Establish your ethos by describing your background, your relationship
to the product/service, the length of time you've used it or known about it.
Establish your logos, too:  in a thesis, tell what you expected and whether or
not your subject met those expectations.

The
rest depends on specifics.  Get into them.  Write paragraphs that have one idea
each and that tell, exactly, what the product/service did or did not do to meet
your expectations.

Your
conclusion should either
1) reinforce your positive review of the
product/service or 2) offer an alternative if you've written a negative
review.  
Successful drafts will:
1. Be 2-3 pages in length. 

2. Follow APA formatting rules