Melancholy in Porto is an odd FM. Two missions long, with a very tenuous and ridiculous plot (my friends and I giggled a lot at how extremely Not How Nuclear Power Or Anything Else Works the story was), no combat or enemies and nothing to do but hunt loot, it doesn't sound like normal Thief 2 fare. And indeed it isn't. What it is (at least the 2018 remaster, which you should seek out rather than the 2009 original even if details like a photograph of Marcelo Rebelo de Sousa introduce some interesting continuity problems; because it's much improved) is a beautiful and interesting tour of the aesthetic and cultural vibe of Portugal's second largest city, Porto.

My recommended serving suggestion for Melancholy in Porto is as follows: You yourself are not Portuguese, but your friend group you stream Thief FMs to on Discord contains one (1) person who is. Start the FM, stream it in a voice chat with them all, and wander lazily about the FM's two fanciful levels in search of loot until your friend excitedly points out a photograph, brand, architectural feature or cultural habit she strongly recognises as uniquely Portuguese. Then listen to her explain all about cereal coffee, or identify the authors Portuguese children are taught at school on a poster, or read and translate very pixellated Portuguese text, or make an assertion that she knows exactly the kind of old lady who'd own an apartment like this from the decor, or gently make fun of the grammar mistakes in the readables because they're exactly the kind that she would make and she knows what peculiarities of the differences between Portuguese and English caused them. Have a fun, cute time with your friends.

If you don't have a Portuguese friend, you might try the FM anyway but I don't know if you'll get much out of it. Similarly if you have more than one, try showing them all at once and see what they disagree on, I'd love to hear about it personally. In any case I'd recommend playing on Easy. The only objective that changes is the loot target and the themes and tempo of the experience don't lend themselves well to the kind of fastidious corner-scouring other FMs might induce.

Is Melancholy in Porto a good FM? I don't know. By Thief standards it's pretty weird. No real stealth involved and a non-City universe setting make for a curious choice, as well as rather strange objectives (in the first mission you are asked to check in on an old lady to see if she's doing ok. It is possible to complete this objective, but you will even after meeting her be none the wiser as to the answer to the question) make it not a particularly obvious pick for someone seeking a "Thief" experience. But... I had fun with it. Really nice, wholesome fun, in fact. So it doesn't feel fair or honest to me to give it a bad score.