Pros: You know you'll site will last a long long time without paying hosting fees. It'll be up 24/7 for a lot of years. Cons: You don't get the freedom of putting a lot of features in your site. Google has the right to delete your blog anytime they want to.
now blogspot has a lot of new features which can make it almost like a whole website, you can even make it an ecommerce site to sell your things
Using Blogspot is suitable for beginners who is no familiar with blog writing. It is user friendly too. But its too bad you can't control certain keys that you want and it can be closed and you can get frustrated if you had it with you for many years. You can start with it but later get your own domain & hosting. have a sense of ownership is great.
I also intend to use wordpress, because they may someday google will close 306 Blogspot similar to yahoo, but really difficult for me when the new wordpress. I'm used to using Blogspot.
Advantage: You can create blog right away without paying single cent. Disadvantage: You blog might ban once it generate high traffic.
I like Blogger because it's free & easy to get started. Cons are that it is a subdomain, Google can shut it down, and you have to comply with Google terms. Their new templates & design features are very helpful & easy to use. You can now easily make a pretty clean looking website that doesn't even look like a blog. Blogger's code can be more lengthy than other platforms. This may make your blog/site less SEO friendly.
I dont find any disadvantages in blogger unless you are a pro. For beginners it is the perfect thing to try out what ever they want. More over it is free of cost, free themes. And you can optimize money with your site through adsense.
Best way to start online is with a Self-Hosted Site - preferably a Self-Hosted Wordpress Site. Using a free Blog like Blogspot will not get you the results you want online. It will actually take you a lot longer to build good traffic to a free blog site like that. Plus you do not have 100% control of the site and the design so that alone will get you frustrated sometimes. I personally use these free blog sites like Blogspot.com for backlinks to my main site. I write blog posts linking back to my main site and then I give those backlinks (from blogspot) more backlinks so that way my main site will get a lot of link juice! You can still make it happen with a free blog site but you will work way more and it will take way longer to see results instead of a self-hosted site where you can get results way faster. This is my recommendation when it comes to building a website online with the purpose of making money online with it. The cool people above me have already explained the down-side and up-side of running a Blogspot site. I hope this info can help you in any way possible! Much success!