I was a very early adaptor when it came to the PlayStation Vita. I actually got it a week early, since I was working at Sucker Punch Productions at the time and Sony was nice enough to send all employees their Vita a week early. It is a great machines, but after playing Uncharted: Golden Abyss, Escape Plan, MLB The Show, and Ultimate Ghosts 'n Goblins it ended up on my shelf gaining dust. For a while. Actually a really long time. Over a year actually.
It wasn't until I downloaded Spelunky on my PS3/Vita cross buy that I decided to dust it off. I already had Spelunky on my Xbox 360, but heard nothing but great things about the Daily Challenges and figured the price was right to get it. I fired it up on my PS3, and while I had fun it didn't really grab me. A couple days later I figured I'd try it on my Vita. So I went to my bookshelf. Grabbed my Vita to have it be dead. Plugged it in and charged it up. Reset the date and time and downloaded Spelunky.
This is probably the best thing that could have happened to my Vita. Spelunky has become my go to game at this point. It has the perfect mix of challenge and enjoyment, though there have been many times that I wanted to throw my Vita out of frustration. Spelunky in my opinion is the perfect handheld game. Games are quick, so you are never tied down. The mechanics are simple to pick up, but incredibly hard to master. The Daily Challenges has become one of the best post release updates I can remember in a game. Checking the leaderboards to see where you compare with your friends is perfect.
Really all I can say is if you have a Vita and you don't own Spelunky, that you are missing out. Do yourself a favor and just download it. It isn't that much and worth every cent.