Advantages of using web-templates:
1. Time saved in setting the patterns, colors, themes and layout of a website.
2. Choose from the variety of options, you will have the glimse of the site in the making or will be for you.If designed by professionals, these are very good in visualization and usability.
3. Save money as templates are cheaper (some are free too) than the total cost of building/developing from scratch.
4. ‘Comparatively’ easy customization is possible as compared with actual coding.Most of the templates can be customized by anyone having basic HTML/CSS knowledge.Some WYSIWYG software (Editors) runs on any windows computer to help you out.
Disadvantages of using web-templates:
1. Lost identity: Templates are not unique, they are globally distributed and chances are many websites might be using them on the www.
2. High level customization requires proper knowledge of web designing softwares and some coding too.
3. Generally for a small site with static pages on a limited number, templates are fine. Real prob. arises for dnynamic sites with changing the result page structures.
4. Templates generate a lot of useless code, not good for understanding and navigation sometimes.
5. Considering SEO (Search Engine Optimization) point of view, you need to work on many details, such as Meta tags, attributes, urls and usability for each page.