One thing I've found with any type of review promotion I've done is to be completely honest.

That means spellling out the good and the bad about the product.

No product is going to be perfect and there are always some things you may like to have been done differently or better.

By throwing in one or two little negatives (in an overall positive review) it shows a lot more credibility than someone who gives a "hypey" review.

One product I promoted to my list before with a review converted at over 10% because of it.

I guess my point is, no matter how much info you give away, people are going to be skeptical to some degree. If you claim the product is the best thing ever, people may not believe what you're saying, but if you sound like you're giving an honest review, it gives you much more credibility.

Hope this helps,

Richard