For many the holy grail of text editors is Textmate. In a very short time it became an indispensable tool for many, many programmers and sysadmins.
Then it stagnated horribly, it gets updated perhaps once per year (and then only to keep it running on the new OS release), and god forbid you find a bug: it will probably never be fixed.
(As I write this there is an alpha promised by Xmas. Many are understandably cynical about this.)
A bunch of projects started up to fill the vacuum created by TM2’s vaporware status. Without sounding too negative on what was an incredible amount of work, they’ve managed to re-implement much of TM1 in the time it took to get TM2 to alpha status. That said making your app compatible with the huge TM1 ecosystem (and what may be the TM2 ecosystem) is an obvious good design call.
Anyway, the two I had immediate access to are Vico and Sublime Text 2. More on Sublime Text 2 later.
To reduce it to the simplest description, Vico is a vi implementation in Cocoa (or at any rate, Mac-native) that is mostly TM-compatible (themes and bundles).
(Also note: I’m sort of unfairly conflating vi and vim here. Pedants, don’t freak out. Hopefully you’ll get what I mean.)
Whether or not you consider vi’s modal editing a plus or minus is not really even worth debating. If you don’t like modal editing, don’t bother to even try any modal editor.
Vico supports a pretty finite subset of vi commands, but enough that you’ll preserve basic muscle-memory when editing. As near as I can tell, commands aren’t as “composable” as a real vi, but that’s where the bundles take over.
Vico supports a subset of TM bundles, so you can probably drop in some functionality that would normally be done with vim macros or scripts.
You can also “drive” Vico’s functionality with built-in scripting using the Nu language. Nu is the (perhaps unholy?) fusion of LISP and Objective-C/Cocoa. And example of using Nu scripting to perform an editor task (automatically hard-wrapping text in this case) is on the Vico blog.
Is that any better than Vim script, or ELisp? I dunno. Vico seems like too much mashed together. It’s in a weird place: if you’re determined to retain modal editing, why not just use MacVim? Well, MacVim is … not so much ugly as plain. So, assuming the creator can keep up with the state of the art enough to keep the users happy, it’s a nice way to appeal to modal editor junkies who somehow don’t fancy MacVim.
But what of the people coming from TM? Isn’t modal editing a huge change, even if it lets them keep some of their workflow? OK, you’re addicted to some set of TM features, but hopping into the world of modal editing seems like as big a jump as switching to some other editor (BBEdit, etc).
Anyway, Vico is an interesting project and I sincerely hope it stays around for a long time: I’m hugely in favor of taking “venerable” Unix concepts and wrapping them in modern clothes.