Service Pack 1 for Visual Studio 2010 does include a graphical designer, although you need to install additional tools in order to enable this.
It's not as full featured as the experience of using SQL Server Management Studio against a "full" SQL Server or SQL Express database, but nonetheless when enabled it looks like this:
Scott Guthrie did a blog post regarding VS2010 SP1 and SQL CE a little while ago (when VS2010 SP1 was still in beta). In that post he points to an additional file that is required on top of VS2010 SP1 that enables the tooling support.
You can enable SQL CE tooling support
within VS 2010 by first installing VS
2010 SP1 (beta).
Once SP1 is installed, you’ll also
then need to install the SQL CE Tools
for Visual Studio download. This
is a separate download that enables
the SQL CE tooling support for VS 2010
Note that, at the moment, this tooling seems geared for the BETA version of VS2010 SP1, and the CTP of SQL Server Compact 4.0. I have, however, used this "tooling installation" myself against the "final" version of SQL Server Compact 4.0, and it continued to work.
Hopefully, the SQL CE & Visual Studio teams will do a "refresh" of this additional tooling installation for the final version of VS2010 SP1.
A recent ScottGu twitter post has stated that:
We will also have a WebPI package
available Monday that auto-installs
VS10 SP1 and additional web goodies
(IIS Express, SQL CE Tools)
The "Monday" he's talking about should be Monday 14th March 2011, so once that ships, you can download the SQL CE Tools and install them "on top of" the Visual Studio 2010 Service Pack 1, and you'll be good to go with all things SQL Server Compact 4.0 !