Sorry, but not for £40. I'd pay £20 for this and all Vita games that don't span 100's of hours.
You can argue that there is user generated content, which could potentially keep you busy for even longer, but if it's anything like the previous LBP's, it'll be jam packed with 1 minute experiences that are little to do with the actual game (like a B-rated shmup, or a mediocre pinball table). I want to see actual levels, that are similar to the campaign levels, only more challenging, more exciting and imaginative. Sadly, there are only a few of these, amongst the millions upon millions of user generated garbage.