I disagree on the previous answers. It depends on your customers/users.
For example, we have a platform where customers and users have to sign in. The login page is identical. Heck, the login portal is identical. No branding, no bells and whistles, just type in username and password. Never had an issue.
The reason why is clear: logging in isn't a problem, it's how does the person logging in get there and what is the expectation. For the former, we provide links to customers and users in a number of different places, all publicly available, all leading to the same place. For the latter, customers expect to log in from our main webpage (big button that says "login here") or from a direct link. Users expect to log in from a link on their personal pages, or a bookmark we offer.
In all cases, there's the opportunity to enter the platform easily and to do what you need to. Remember, login is for security, not a barrier to entry. Keep it simple and quick.