Will I like this game? Might buy it tomorrow...

The game is godly.
But I'm a bit biased, this is probably one of my favourite games of all time.
There's A LOT of text, but the story is fabulous and full of mysteries and plot twists that will make your head explode, I guarantee it.
Try the demo, if you're not sure! It contains the first hour or so of the game compressed in 10-15 minutes and one of the 16 puzzle rooms.
If you own a DS you should play 999, the prequel, which is also godly. Although it isn't strictly necessary for understanding VLR's plot, it will give a deeper meaning to some characters and twists in VLR.
Characters and story is what drives the experience. You won't be able to put your Vita down.

About the endings. There's a comfortable feature inside the game that lets you jump to any point of the game you've already been, so that getting all endings isn't a terrible task. If you screw up, you can just jump back!
BTW, the endings aren't variations of the same thing. Each and every ending is different and you're required to get at least 9 of them before seeing the True Ending of the game!

Yes! Mind that the EU version only has Japanese voiceovers. If you want the English dub, you must import the game, sadly!
The demo doesn't represent the game quite well, but introduces the characters and setting, so you can see for yourself.
If you don't like the puzzle room, I have two things to say:
1) The one in the demo is one of the worst puzzle rooms.
2) They are a small part of the game! 80% of the game is made from novel sections.

Since you own a Vita there's no reason not to buy the US one. If I may suggest:

http://www.amazon.co.uk/Zero-Escape-Virtues-Last-Reward/dp/B007FMSDUK/ref=sr_1_3?s=videogames&ie=UTF8&qid=1360278312&sr=1-3

This is the US version, since it's published by Aksys. It costs more than the UK one and you have to pay for shipping, but that's the deal!
OR, you can back up your Vita data, create and use an american account and download it from the PS Store, it's up to you!

You're welcome! Let us know what you think about the game!

Boy, oh boy! If you love multiple endings, you're gonna marry this game for how they're executed!

Really glad, people usually think the game has a slow start and gets better on.
If you're liking it already it's a good thing!

Remember that there's always the PSN downloadable version!
Anyways, yes, 999 isn't NECESSARY, but you get a deeper experience in VLR if you played 999 first.