In my opinion, it would be a lot more productive to learn one of the "standard text editors," namely vi(m) or emacs. The learning curve is higher, but it will allow to be very productive on almost any Unix-based operating system.
Textmate is a great product with a lot of useful features right out of the box, and it very Mac-like with its UI and Apple-style keyboard shortcuts. It also has a lot of macros, and you can access a lot of shell commands straight from the menus. However, by hiding all of these details, it makes it more difficult to use a computer that does not have Textmate on it.
Thus, if the "Macness" of a program is very important to you, and you don't mind being dependent on one machine and one proprietary program, then Textmate is certainly worth the cost. If not, then I recommend you save the money and build skills for the future by learning how to work with vim or emacs.
Although most people who use these common programs have to customize them extensively. Using emacs without my .emacs file can be as disorienting as using another editor.
Not sure if you're thinking of TextMate or TextWrangler. TextWrangler does have a Mac-like UI and uses Apple-style keyboard shortcuts. TextMate's UI is not particularly Mac-like, it exposes shell commands quite directly, and most of the macros are shell/ruby/etc scripts.
To illustrate the difference, TextWrangler has a menu command to sort the current document, and a menu command to remove duplicate lines. TextMate has "Filter Through Command" which lets you apply arbitrary command like "sort | uniq" to the current document.
Textmate is a great product with a lot of useful features right out of the box, and it very Mac-like with its UI and Apple-style keyboard shortcuts. It also has a lot of macros, and you can access a lot of shell commands straight from the menus. However, by hiding all of these details, it makes it more difficult to use a computer that does not have Textmate on it.
Thus, if the "Macness" of a program is very important to you, and you don't mind being dependent on one machine and one proprietary program, then Textmate is certainly worth the cost. If not, then I recommend you save the money and build skills for the future by learning how to work with vim or emacs.