We just got back from 3 weeks in Europe with a 9 month old, and I am really glad we didn't let having a baby stop us from going. I think travelling with a 6 month old would be easier, as they're less mobile.
For us, the trickiest things to manage were food and transport. DS was on solids and breastfed. It was sometimes hard to get hold of appropriate food for him (constantly looking for supermarkets in each new city) but if you're staying in one place it would be much simpler.
Transport was sometimes tricky- we took trains and buses as much as possible, but a couple of times we had to use taxis with no baby seats.
We booked apartments for most of our trip. It was great having both a kitchen and a washing machine, and made life easier.
We tried as much as possible to get DS to sleep in his stroller or in the baby carrier while we were out and about, rather than coming back to the apartment.
Dinner was a bit hit and miss, depending on DS's mood and how tired he was. A couple of times he slept in his stroller while we ate, sometimes he sat on our laps while we ate (because Spanish restaurants rarely have high chairs) and a few times when he was a super grump we gave up and got take-away.
We had two flights (about 20 hours in total) to get there. On the way over we left around 5pm and he slept a lot of the way (unfortunately on us, rather than in the bassinet). The flight back left at 11am and wasn't so good- tiring for all 3 of us- but survivable!
I'd say go for it!