STUGOTS  I switched to this from NetNewsWire, after the NNW Beta update nuked most of my subscriptions.

I find Vienna to be very stable, with a cleaner UI than what I've been used to with NetNewsWire. There's a better use of real estate. The overall visual design looks far more polished than what you usually find in an open-source project.

The default fonts are OK but there are better choices, IMHO. They are easy to change in the preferences.

The only feature I miss is synchronization with a service out on the web, so I can share my feeds between work and home. (*Not* Google Reader, TYVM.) From what I gather in the support forum, synchronization is one of the new features being considered.  
(Version 2.3.3.2304)

ROB.H  Ticks all the right boxes for me.

Now that NetNewsWire is going commercial/ad-supported, Vienna is a great free alternative. Clean uncluttered interface (with some interesting visual styles to choose from if you like that sort of thing) plus it's easy and intuitive to use.

The only thing missing really is the sync features of NetNewsWire, but then I'm trying to ween myself off hours of reading newsfeeds every day on every device I own, so that's probably a good thing!   
(Version 2.3.3.2304)

JOSHEWAH  I like this app a lot. I wish that flash and audio/video wouldn't reload every time I switched tabs though. If I am checking out a song from a blog in a tab and go back to read feeds while it plays it cuts it off and starts downloading again when I go back to it.  
(Version 2.2.2.2211b)

CMASON  I just heard that netnewswire was going ad-supported (ironically, it was their own beta update message that mentioned this.) I used to use netnewswire lite and was happy with it and never really needed the "pro" version. I got it anyway once they made it free but never really used any of the advanced features.

I tried newsfire and it looked nice, but didn't have the same 3-pane view I was used to.

So, then I found Vienna. It works great! I loaded up my subscriptions, changed a couple fonts, and that's it. It is doing exactly what I want with a simple interface that looks almost the same as netnewswire. Most importantly, *no ads*! Well done.  
(Version 2.3.4.2305)

MOMIJIGARI  I use this software every day.  
(Version 2.3.2.2303)

IVANOVITCH  A timely update: it was unusable with Remote Buddy open at the same time (made Vienna uncontrollable, oddly). Further, the display bugs introduced with Leopard now appear to be ironed out. No more truncated scrollbars or icons.

What's missing:

Still no icon to indicate that a headline has been opened in external browser: only option is to display read/unread and to manually flag item.

Also difficult to re-sort headlines by date (up or down) without doubling size of pane used for headlines (I use condensed layout to emulate previously purchased RSS readers).

Apart from this, it works remarkably well, and the price is brilliant value. Like others, I bought other readers but grew disappointed with the direction of development and features. I'm now happily stuck with Vienna.  
(Version 2.2.1.2210)

PENGUIRL  I came back to Vienna after NetNewsWire switched their synching from NewsGator to Google and raised the system requirements to 10.5. It has a nice UI, good functionality, and it's the only RSS/Atom reader I've tried that imported my feeds in the same folder hierarchy that they were exported in. So far my only complaints are font related, increasing the size of the article headlines font causes the date and time to be cut off by the headline below it, and there is no font settings for the article summary or the full articles. The only way to make them larger is to force all fonts to a larger minimum size, thus bringing up the previously mentioned issue.

At this time I don't need synchronization but it would be a nice feature to have for the future. All in all Vienna is the best of it's class.  
(Version 2.3.4.2305)

ITISTODAY  - Builtin tabbed web browser!

- Fast!

- Support for folders and nested folders!

- Email-like view to show article titles from either a feed, or a group of feeds!

- Open source!

- Smart folders!

- Easy flagging!

What's not to like?? This is the best news reader I've come across, bar none.  
(Version 2.3.4.2305)

TINGTING  Needs more toolbar button options like "mark all read" "refresh" just a single feed. And not a drop down menu like it has where you get carpal tunnel click-scroll-click. One click. otherwise cool, I hope it grows in the right direction.  
(Version 2.2.0)

ZX81  I hate Vienna!

I bought NetNewsWire and Newsfire and discovered Vienna afterwards!!! Now I don't use the readers I have bought anymore and I've swithched to the free one...It's fast, easy to configure and use, can import and export my list of suscriptions (I exported it to OmniOutliner). The builtin browser is just great and seems to be able to open any Web page and download files (which isn't the case of NetNewsWire ; I've tested quite a few pages).

Very stable. Great app.  
(Version 2.2.0)