Caveats:

- If you intend to work within Academia, you may occasionally have to deal with fairly incompetent professors. It depends on the research unit and area, but there tends to be a certain amount of people who got full tenure in the past by connections and self-publications only. Needless to say that there are also some very good people. For example, at our institute about 50% are foreigners with excellent publications in English.

- Rents have skyrocketed during the past years in all beautiful areas of Lisbon. It's still not even comparable to SF, of course, but you need to calculate around 800 for a decent 2 room apartment. Housing prices have also gone up, but if you have the money it would be a safe investment - they'll continue to rise for quite a while. (Is there any major capital where they don't rise?)

- Social hierarchies and "respect" (in the sense of brown-nosing) are generally more important than in the north of Europe. Portuguese are very friendly towards foreigners, but they can be rather unfriendly among themselves. It's a kind of social pressure and artificial politeness/respect that can be very unappealing in the long run. You can never say straightforward to your boss what you think, no matter how right you are. Critique always needs to be very indirect.

I cannot say anything about the startup scene, because I'm not familiar with it. I suppose it's generally harder to obtain VC funding or bank credits than in the US. Starting a company is very easy, though, for a small company it suffices to hire a freelance account. IRS is also outstanding and can be done online within 5 minutes. The only downside is that as a foreigner you don't get a citizen card, which means that you have to go to local authorities in person instead of doing it online, too. Traditionally, Lisboagas (for natural gas delivery) and the Social Security authority suck, every other authority or company I've dealt with in the past 10 years was super-friendly and professional.

Overall, I can totally recommend Lisbon for anyone who wants high quality of living combined with low costs of living. I have no plans of ever moving away again and instead plan to open my own little software company in case my postdoc funding ever dries out - so far it's still going well in Academia though.