Anything that is free is suspect. The same applies to free web hosting services. They may or may not provide the level of reliability that you need. So, you have to be careful when you choose a free web host.
You should also be ready to accept several restrictions. These include:
A free hosting service may place advertisements, including those of your competitors. This is the main source of revenue for a free host. But these advertisements can prove an irritant for your customers who may not like their browsing experience to be affected by these ads.
With a free hosting plan you may get very little support or no support at all. A FAQ page may be your only support. What's more you cannot expect things to change even if you complain.
A free hosting plan may look good on paper but may have very little practical utility. There may be frequent server breakdowns; the bandwidth may not be enough to support the needs of your site; there may be no scalability; or there may be thousands of other websites competing for the same resources.
Free web hosts don't offer much storage space and even restrict the type of files you can use. For instance, you may not be allowed to upload files that need a lot of bandwidth, like MP3 files. This can severely limit the utility of your website.
Free web hosts may also force you to use a sub-domain, which makes your ID much longer than it would have been, if you had your own domain name. You may end up loosing several customers because they cannot remember your domain name.
These are genuine disadvantages. You must remember that the net is a very unforgiving medium. Visitors don't return to a website that suffers from frequent technical problems, which is cluttered or which cramps their navigation.
A free host must be avoided if you want to set up a business website because the loss can be much higher - in terms of customers lost -- than the actual gain. You will also not be able to display the goods the way you want or offer support services that are expected from a good website.
However, you can consider a free web host if your website is an information website or a personal website. But even this should be for a limited period. You must be ready to invest money if you want your website to grow.