So I've been using this new Google Reader for a full hour now and here are a few observations.
Note that my background with Google Reader is that I read 312 feeds through it and do end my day with 0 unreads. This means that, on most month, I consume about 30,000 stories, seldom clicking away from the reader itself as I read mostly full feeds.
The first thing that struck me is how much slower this reader is. There seems to be a refresh on every new move forward, which was less noticeable on the previous version, if at all. There also seems to be a substantially slower response time, on the order of a couple of seconds. This is particularly noticeable if you read the HN firehose feed and try to "N" through the entries.
The left column is mostly OK and it does seem cleaner than the previous version.
The top is dreadful, with a new line taking about 20% of the screen real-estate. While this gives a more "airy" feeling to the Reader, this is at the cost of displaying less content on the page. This is the first glaring UI problem but it's not the worse.
For some odd reason, they seem to have decided to limit the flexibility of the content in the feeds, with text stopping at about 800 pixels and the left of the space on the right being left blank. This creates a substantial imbalance on the screen and makes the whole look feel incomplete. Furthermore, it reduces information density per entry displayed.
Starred is now a sharper edged icons, which is substantially less rounded than the previous version. The presence of 2 stars (one next to the title and one in the toolbar) makes one wonder which one should be used. That's confusing.
The absence of share is a major bummer. In my previous workflow, I would click share (1 click) when I found something interesting and move on. I had setup an RSS reader that would pick up my shared items and pass them on to Twitter, Facebook, and others. This meant that 1 click allowed me to share to social networks without leaving Google Reader. In order to reproduce the same process, I can now "Send to" a service. To do so, I first click "Send to" and then click on the appropriate service, which opens another window. In that service, I can then press a button and share things through that service. I then close that service window and click on the Google Reader tab to get back to my Reader workflow. This is a total of 5 clicks where there once was 1. Doesn't strike me as much of an improvement.
All and all, I have to say, Google Reader may be a fine upgrade for people who don't use RSS readers. But for anyone who's serious about consuming content over RSS, Google has done a substantial disservice by taking what was once a great service for power users and driving it into the ditch.
The net-net of all this is that Google Reader, a service where I spent most of my online reading time will soon end up being replaced by another RSS reader (at least one more suited to my usage) and Google will lose a substantial amount of my online time in the process. I'm sure they won't mind (or even notice) but I suspect they will be surprised when a Google Reader replacement service arises away from them and finds a dedicated following.