Honestly can't remember what half of them are like but I'll try...
If I don't write anything next to it I either can't remember it, or nothing stood out.
UK
London Stansted - I actually quite like it, although the area through security is too small and cramped compared to the check in area which is HUGE.
London Heathrow - Totally depends on the Terminal. T5 is great, 4 is probably the worst as it's just a single concourse with nothing to do.
London Gatwick - It has become a lot better under the new ownership. No complaints really - the car parks are really good.
London Luton - Absolutely DIRE. The car parks are horrible and the departure lounge is far to small for the amount of people that use it. There is plenty of room around the gates but they keep you penned in the tiny lounge like cattle for as long as possible (I know this is commonplace, but at least have enough space for it). There are no seats either. Also full of package holiday peasants - avoid the summer holidays at all costs!
Birmingham - Really good, probably my favourite. Minimal faff and a nice mix of restaurants and fast food. Well connected.
Manchester - Also quite good. Security took forever, but I probably just caught it on a bad day.
Coventry - Thomsonfly did a few commercial flights here between 2004 and 2009 or something, used it to fly to Amsterdam in 2006. It was literally a portacabin with 2 check in desks. Due to the tiny operations there was no faff, as everyone at the airport was going on the same flight. It was just fab due to it being 15mins from my house. No facilities whatsoever though. They couldn't get planning permission for a permanent terminal so the airline stopped using the airport.
East Midlands - A smaller version of Luton.
*Gibraltar - Recently rebuilt so is nice and pretty, despite being small. It has a huge outdoor terrace overlooking the Runway which is a nice touch. Often closes during bad weather though </3.
Germany
Frankfurt-Hahn - Can't really remember it, typical Ryanair airport I think. In the middle of nowhere.
Italy
Turin - Quite a small regional airport. Could be good but ruined by busses from the plane to the terminal (my biggest pet hate at airports).
Rome Ciampino - Gross. Secondary airport.
Sweden
Göteborg City - The only Ryanair airport which is actually closer to town than the larger airport. In 2006 it was just a tin shed and you had to get your own luggage off the trailer thing (not that we had any luggage, obv). They were just starting work on it so it's probably completely different now.
Finland
Tampere - Another tiny airport. Walked straight off the plane and outside so no complaints really.
Helsinki
Norway
Oslo - Smaller than I expected but it was fairly modern and had free wifi <3.
Iceland
Reykjavík-Keflavík - New terminal but badly designed. Arriving passengers get spat out into the departure lounge, with the departing passengers, then have to follow a ridiculous route through the whole lounge to get to passport control. It was really weird and confusing.
Spain
Reus - Ryanair
Girona - Ryanair
Malaga - Old and gross
Madrid Barajas
Palma de Mallorca
Menorca
Tenerife South
Lanzarote
Portugal
Faro
Serbia
Belgrade
Croatia
Dubrovnik
Netherlands
Amsterdam Schiphol
Russia
Moscow Domodedovo - Really bad. It has a good rail link but that's about it. Extremely expensive, excessive security (can't really hold this against them as it has been bombed about 5 times), disorganised.
Malta
Malta
Czech Republic
Prague
Hungary
Budapest
Poland
Krakow
Estonia
Tallinn
Lithuania
Kaunas
Ukraine
Kiev Zhuliany
Bulgaria
Sofia - Gross and falling apart, in need of a revamp. No train link, but I think the Metro is being extented to reach it eventually.
Romania
Bucharest - I was expecting another Sofia but was pleasently surprised, plenty of seating and food options at reasonable prices. Not sure about the transport links but taxis are dirt cheap.
Greece
Kefalonia
Turkey
Dalaman - It was a proper 70s airport but has since been rebuilt so I can't really comment.
Bodrum
Ireland
Dublin - it was basically Manchester or Birmingham but with more irish accents. Gets extra points for having a McDonalds.
Israel
Tel Aviv Ben Gurion - Potentially fab but completely ruined by the extreme security. It doesn't make any sense because they don't give a crap when you enter the country, but on departure you get an hour long interrogation. They will open your bag and swab every dirty sock and pair of underwear individually. We didn't even get to see the departure lounge because it took 3 hours to get through security (this was before the check in desk).
Egypt
Sharm el Sheikh - Old, cramped, smokey, smelly.
Morocco
Marrakesh - See Sharm el Sheikh.
Tunisia
Tunis - See Marrakesh.
Jordan
Queen Alia - Tired and old 70s concrete. Used it in 2012 and a completely new terminal was being built to replace the old one.
Qatar
Doha - I have used Doha to transit (2013) and also as a destination in itself (2011). I love Qatar Airways but Doha really lets them down as their primary hub - it's far to small for the amount of traffic it receives and simply cannot cope. They run it quite efficiently though considering how much of a dump it is. Luckily, a gigantic brand new airport is opening a few miles to the west very soon to replace this one.
United Arab Emirates
Dubai - Fab. Amazing choice of food outlets, duty free and very well connected to the city. Everything is absolutely massive so you never feel suffocated.
Singapore
Singapore Changi - One of my personal faves. One terminal has a swimming pool and another has a butterfly garden. There is also free Wifi. The only slight gripe is that they make you go through security again when in transit, but this seems to be the trend everywhere now.
Indonesia
Bali Ngurah Rai - A real let down. It's a brand new airport but they haven't bothered finishing it. It's fine until you go through security and then realise there are no facilities - it's just one huge concourse with loads of carpet. The only refreshments on offer were temporary stands selling hot dogs.
Hong Kong
Hong Kong - Kind of like Singapore but without the butterfly garden. Also one of my faves.
China
Shanghai Pudong
Beijing Capital
United States
Miami - Vile.
LAX - Vile.
Philadelphia
Newark
Manchester (NH)