Is it? It's not a great software but doesn't appear overly buggy or unmaintained compared to other office products. Office products and browser compatability are always an issue.
IDK. Skype used to be reliable, but now it seems utterly useless. They took ages, about a year if I'm remembering right, to bring out Skype for their own Windows Mobile platform. I've personally hit a bug where the web interface allowed you to set a password that was incompatible with the app (too long I think).
The enterprise version isn't production ready for serious use. $FORTUNE_500 where I'm at really wanted to make it work - I suppose we pay for it on a per-seat basis along with the Office 365 product - but client disconnects with >100 users for an internal webinar on our internal network resulted in an embarassingly broken presentation and a decision to bail off to a different vendor's product.