Sibylle and I went for a 5-day vacation in Portugal's capital, which was much beautiful than expected. Honestly, I can recommend Lisbon to anyone, especially off-season, when it's not crowded at all.
The city center has great charm, despite the obvious signs of neglect with many houses. It's just really, really pretty, and walking up and down the hills was totally worth the effort of taking it in at a leisurely pace. Even at the beginning of March the weather was great – we spent Saturday basking in the sun on the nearby beach in Estoril (much prettier than the one in Cascais, right next to it). Another daytrip was to Sintra – trains are very cheap, and the traditional little cakes alone worth the journey, not to speak of the cute town and impressive castles. It's not for nothing a Unesco World Heritage Site.
Also, the people are very friendly, a lot of them speak at least a bit of English or French – if we looked lost for even a second, someone always came to us and helped us find our way.
You can find more photos in my Flickr album.