The main problem with it is that each tab has its own process. That doesn’t work for my use of Mac browser to keep various tech references (e.g. iPhone SDK docs) open while programming (since the built in xcode doc viewer is horrible). With 8-12 browser windows (one for each sub-area of interest) and each 6-8 tabs per window, browser would use up to ~100 processes (with all the memory & CPU overhead that goes with each). That’s absurd. Combined with the annoyance of having Google spyware on the system all the time, I’ll keep Safari.
It does seem wasteful, but it fits with Google's longer term browser-as-OS model. Its advantage is you can crater one tab, but the other browser tabs being their own process, are unaffected.