EmEditor Professional (which costs £34 with a 30-day free trial) is a powerful text editing program with many features that can make it useful to programmers, Web designers, system administrators, and anyone else who regularly works with unformatted text.
The interface for EmEditor is very standard - a variety of panels which can be shown or hidden, with a central tabbed editing area. Slightly confusingly, some of the side panels are controlled by 'View' and others by 'Plug-Ins'. While this makes development sense, it's not instantly intuitive where to look to turn on or off a feature. This is a common thread throughout EmEditor: It's often a bit more of a task than it should be to figure out how to use a particular aspect of the program, but there are enough cool bits in the program that it can be worth it, especially if you're not already committed to another text editor and thoroughly indoctrinated in its quirks.
EmEditor documentation isn't the best it could be, being both sparse and peppered with questionable English, but it does get the job done. Simply put, while there were things I felt I should be able to figure out just from looking at menus, that I instead needed to go to the documentation for, said documentation did answer my questions with minimal searching. It also responded to the most obvious and intuitive keywords.
Beyond that, EmEditor has many of the features expected of a professional text editor: multiple copy/paste, vertical or "block" selection, file comparisons (diff), and so on. It does not, however, have a very sophisticated hook into common development tools like Visual Studio; you can set it up as an "external tool", and samples are given to help with this, but there is no automated integration.
Speed-wise, I found EmEditor quite responsive and easy to use. The wealth of configuration options and the ability to quickly change them on a file-by-file basis makes it very useful if you regularly edit a lot of different file types, which I do, jumping from Java to PERL to HTML to CSV regularly in the course of a working day.
EmEditor is under constant development; a look at the change log shows that EmuraSoft is quick to fix bugs and add features.
EmEditor is inexpensive, powerful, and has many useful features, but it's hard to say it dramatically raises the bar over similar tools, such as UltraEdit, especially if a user is already committed to such a tool and has configured it to their personal tastes. Freeware programs such as NotePad++ also offer a lot of functionality for no price, though EmEdit has code navigation features NotePad++ lacks.
This is a problem in general with programs in mature categories; so much of the core functionality is standard that it's hard to justify changing for a small number of improvements or new features. However, if you're in the market for a text editor and not closely tied to a particular one, EmEditor Professional is very much worth looking at, as it offers an exceptional mix of features and tools at a low price.