Backtrack is a REALLY useful keylogger (it also captures images, but I don't use it for that). It does catch the 'un-versionable' in Lion: comments, typed tweets from Twitter.app, etc. Despite the somewhat clunky UI it's very usable. I was able to find texts from hours before that would not have been saved. All in all it's a better solution than the free logkext that I had (occasionally) been using.
I haven't run into any memory problems or slowdowns yet. EXCEPT for.. read on.
BacktrackBA takes about 40 megs of Ram, and runs in 64-bit. It HAS to run in the background.. else how would it capture your keystrokes? Even in typed comments in twitter or some web form? That's not the beef I have with the dev. This is-
Backtrack's demo mode it is REALLY obnoxious, and in some cases may even wedge your machine as it did with me on Lion.
Let me explain: Every 15 minutes the dev will throw a nuisance dialog to try and get you to register your machine. Fine. Throw the dialog. But then the author overrides your 'Text to Speech' settings and your machine will try to use the default system voice & announce 'Excuse me, Backtrack needs your attention'. BIG NO-NO. Every 15 minutes.
The first time this happened, while I had a number of things open, and I had my system voice set to japanese but OFF. Guess what? My machine froze while Backtrack tried to do the English dialog in Japanese. I have since switched back to English, so now every 15 minutes when the menu item is on it blares in English. Even tho' I have TTS set to OFF.
In another case, by the 3rd or so nuisance dialog the demo can't invoke the system voice, so your Lion machine may freeze. I had this happen WHILE I was writing this review! Fans on, total freeze. I had to ssh into my own MacBook Pro and kill things from the Terminal. This is TOTALLY unforgivable.
So while I find Backtrack very useful, the Dev's obnoxious 'per machine' licensing plus this obnoxious Demo 'feature' left a bad taste in my mouth.
The Dev should DEFINITELY not be using TTS against the users' wishes, and I told him this in email.
I'll leave it to everyone else as to whether it's worth the grief. The features are great. The Dev's licensing terms and demo? He almost lost a sale (while I typed this up, 15 minutes went by: *BEEP* 'Excuse me, Backtrack needs your attention').. if I hadn't already got it via MacZot, I'd probably be trashing it right now. It's THAT obnoxious.
3-4 stars for the features (I'm sure this rating will go up after I lose some typing)
1-2 stars for probably the most obnoxious demo I've ever had to endure. I say this as someone who works in software.