Beeing in a vacation house can be a very satisfying experience – especially if you take a 5 minute break from your work and install Firefox 2.0 on the machine there(that you never really use, thus no risk).
Firefox 2.0 looks totally different from 1.0 – in fact, it is so different that it confused me quite a bit on the first glance. Also, the tab close buttons were rearranged – this reduces mouse movement from 1.x(it always had the tab closer in the top right), but also required me to rethink my ways:
The important lesson learned here is that improving UI can(and will) confuse users. so, try to get your UI right the first time and make small step upgrades – and please,. please, please don’t force a look-and-feel upgrade onto your users!