Site reviews are a great tool in order to check how well your own site was/is being crafted. It can help you enhance some of the bad points and keep you going on the good ones. A reviewer usually lays an eye on everything that's on your site, be it on the front or hidden in the back alleys. One can also check how well your site is doing outside of itself; that is, on directories, article sites, open forums, and much more.

Does it have to be technical only? No, it can focus on things like grammar and orthography, correct marketing campaigns, etc, but it can also lead to talks about programming errors and overall design.

A nice presentation begins with a good navigation system, a not-too-crowded design (some choose too minimalistic and fail because of that), and a good level of correct English (or whatever the language is). The last one is very easy to detect -- you could use an automated tool for typos and a cautious reader for grammar. Also, navigation and design can be analyzed by software, but a good human eye is still better if it goes along with it.

Great content is great content. It will keep your visitors on your site. But how will it affect the ones who are not your visitors? You need a good marketing plan and that can also be made by a reviewer. Looking for the right site to place ads or to get listed is a first choice. Being a frequent web user is, too. But nothing will ever beat interaction. If you don't interact inside your own niche, you're dead meat. Go meet the other people who do similar jobs, that could get your site (or service!) together with theirs, go look for traffic yourself. Search engines help a lot, but if you had invented Coca-Cola, you wouldn't trust yourself to search engines (even if they already existed...). Go out, get your hands dirty, and meet some people. It will definitely get yourself some traffic. Some quality traffic.

A reviewer will help you in depth with these (or more) steps.