I've always been a bit leery of the TPVs, for several reasons. The absolutely relentless promotion of Phoenix/Firestorm by their advocates evidently works, in terms of attracting "market share", but it is very wearisome to those of us who don't use it... frankly, the sheer rudeness of some of their more vocal supporters is offputting in itself; I've had otherwise reasonable people tell me I'm an "amateur" for not adopting their viewer. One of the reasons LL cited for eliminating that TPV feature that tells you what viewer people are in was that new users who hadn't switched to Phoenix/Firestorm were being verbally bullied and abused over their choice... and, you know what? I believe it.
I was also around for the whole Emerald fiasco, which doesn't help... and, besides, I want to keep up with the latest advances in viewer technology, and (as I think I've said before) these are more likely to come along in the official LL viewer than in a TPV - particularly a TPV whose main selling point is "basically, we are never going to change the interface". And, let me reiterate a point here, too; unless you're used to it, the old V1.23 interface sucks.
So, no Phoenix or Firestorm for me (actually, I did try Phoenix, once. Besides the overall suckiness of the old-style interface, the default colour scheme struck me as eye-bleedingly horrible. I know you can change it... or I could just, y'know, use something else, which I actually prefer!) But Catznip seemed to be interesting, and I decided to give it a little whirl. As I said, I was pleasantly surprised.
For a start, it is a V3 based viewer, none of the old (sucky. Did I mention it was sucky, yet?) interface about it. So, I have my outfits and my received items and my flexible toolbars, and niceties like legible fonts and menu bars that aren't a horrible clutter. Also, the big thing that Catznip's dev team seem to be touting, above everything else, is stability. This viewer clocks up enviably low crash rates, and the developers seem to be enthusiastic about that, and think it is something to aim for. I approve of this. I've said a few times that, had I the choice, I would happily declare a moratorium on new features for six months or so and put all LL's dev teams onto fixing the damn bugs already. Since my system is prone to falling over in a gentle breeze (I suppose my running the bleeding-edge dev version of V3 doesn't exactly help there), I am in favour of a dev team that regards Not Crashing as a priority goal.
I didn't explore all of Catznip's features last night (I only had a few hours, and most of that time was spent in traditional SL things rather than testing viewer features), but I formed a more or less positive impression. My frame rate was lousy (it always is) but it was slightly less lousy than usual, and I didn't crash. The IM interface was a bit more old-school that I would like... but that was offset by the profiles viewer also being old-school, and that I did like; as an inveterate profile perv, I have always found the new, slow-loading HTML profiles an irritation, and being able to get a quick view of people's groups and interests came as a welcome flash of nostalgia. (So, I couldn't read anyone's
So, yes. Catznip. I think this one may well supplant Singularity as my go-to TPV of choice. When I choose to go to a TPV at all, of course, which will not be often. But I can live with this one, I think.