That is not really hard, considering the lack of options in the built-in widget, but the New Tag Cloud has so many!
You can define the font sizes, the number of tags, the style of the links, that appears between the tags and how the tags are sorted.
You can filter the tags, or restrict the tag to a particular set of categories. You can even create multiple clouds!
I use the New Tag Cloud on a number of sites that have customised themes, especially if they do not have widgetized sidebars, as the cloud can also be positioned directly within the theme.
If you need more options than the built-in widget gives you, then you should install it and make use of the features available.
On the other hand, if you do not need those features, then you may consider staying with the built-in cloud to keep the number of installed plug-ins down.
So even though I recommend this plug-in and use it elsewhere, I am still undecided as to whether I want to install it on this blog.
What do you think I should do?