Please give me your feedback on this itinerary

It looks doable. And I agree wiht you that it's too much too fast. My suggestion would be to skip one or two of your stops (Interlaken? it seems like the odd man out here among otherwise top-tier destinations) and slow down just a bit. I'd definitely give Venice more time.

I think that, despite your friend contributing the points, you both have to agree on the destinations. What is it you really want to see? I think much of your day in Prague will be wiped out by jet lag, so either schedule more time there or cut them out....otherwise, it'll be a waste. I agree with David that Interlaken should probably be left out. In fact, I would argue that, this time around, Venice is probably best left out too. Why not concentrate on the "northern European" experience this time around, say A'dam to Prague, then Munich, then Paris? That gives you, say 3 full days in each city....and you could easily fill those three days in those cities if you've never been there before.

Wow, I am tired just looking at it. When I think about traveling from one city to the next I consider not only the time involved but the frustrations involved in leaving a hotel, getting on transportation and finding another hotel. I hate repacking. I think you are right, may be a little hectic. I'm still trying to squeeze Paris into 2 weeks. Maybe I would try an itinerary like yours if I had more money?? Why don't you check into the cancellation policies in case you guys decide to "wing it" and chop a destination off?

I think I would drop Prague and Interlaken add time to Venice then Munich and/or Amsterdam and/or Paris. Venice needs more time. Even though you have seen Amsterdam perhaps there are some daytrips you can take, and certainly Munich offers much to see along with some day trips - Neuschwanstein Castle for one. Paris offers so much as well and daytrips from there are plentiful - Versailles for instance. Remember each one of these cities you could spend your entire vacation and not see them all. So an extra night or two in them will not be wasted and it will allow you to sit and relax a bit and really enjoy your time there.