It was a little slow when I first tried it (the famous Slashdot effect multiplied by thousands of other web surfers) and was throwing up errors somewhat often. However just now, things seem to be a lot more stable.
Google Reader is very similar to Gmail in many ways, but in other ways it is very different. I love the way you can easily scroll through feeds using up/down buttons. By far it seems like the easiest RSS reader I have seen yet to go through a mass of new entries in just a few minutes. Loading times right now seem to be pretty quick and should only get quicker.
I also love the quick search you can do to find a feed you are looking for. In classic Google fashion, it is usually very good at finding what your looking for. Easy to subscribe to feeds and easy to organize them using tags.
Feedlounge was a great stab at an AJAX feed reader, but I am very impressed by this early version of Google Reader. Feedlounge for whatever reason made scanning a large list of new entries really hard. I just never got comfortable using it.
I also like how Google Reader opens a link in a new window (or in my case, tab thanks to Firefox). Feedlounge doesn’t do this while Bloglines did.
So I just imported my OPML file and all of my feeds after a minute or two showed up. Looks like I am going to try this out for a couple to weeks to see if I can switch to Google Reader full-time.
One thing is for certain, I have no reason to use Bloglines anymore.