I went to Cubana once and it didn't rate well even as an impromptu meal with a mate.
If you want vibrant, a couple of minutes' walk away on The Cut is Tas turkish restaurant, they usually have a fun atmosphere (probably a guitar player) and good food. There are also branches in Borough High St and opposite Shakespeare's Globe.
Definitely not! It's more of a bar than a restaurant - the food's OK, but nothing special. They wouldn't even serve me a Caprhina as they said it took too long to crush the limes and were only doing Mojitos that night...
Being close to the station, it's a popular haunt for after work drinks and I'd really look for somewhere else if you want a quiet romantic evening.
You could try the Waterloo Bar and Kitchen? More romantic, but £30-40 per head:
If you like Chinese you could try Dragon Castle in Elephant and Castle - often said to be one of the best Chinese restaurants in London. Also on The Cut is the Young Vic where there is a good bar and restaurant.
Perhaps I'm being a bit naive (or maybe my partner is unduly picky) but I don't think I'd get much credit if I took her to one of the serviceable but decidedly unromantic Indian restaurants on The Cut for Valentine's Day.
Experience suggests you should either dig deep into your pocket or - to create a favourable impression in a much more sincere but perhaps also slightly risky way - cook for her yourself, eat by candlelight, wash up afterwards, and serve her favourite wine.
Go for any restaurant near Tower Bridge [Pont if you are playing for keeps, Dim T if you are seeing how it goes... Dim T] and book the Champagne on Tower Bridge to go with it - did it 2 years ago - unique, romantic and at only £10 per person including champagne you are all set for excellent return on investment....
'...you are all set for excellent return on investment....'
Good suggestion, I've I was a woman I'd love you for it Ben. I ran past there last night on my routine jog and noted how nice the area is looking since they have put in a good deal of atmospheric lighting, though I'd did raise an eyebrow to H.M.S Belfast being made to look pretty.
Dress up warm though it'll be pretty cold up there, though I guess love might help.