I've played around 30 hours of Spelunky at this point. I am worlds better at it than I was when I first picked it up. But on my best run I still haven't even gotten to the final world yet. More often than not I can't even make it past the second world. Truth be told, I just died on the very first level on the last game I played.
So why am I giving Spelunky a thumbs up?
Because the game is fun. And fair. Mostly fair, at least.
Let's get this out of the way: Spelunky is a hard game. 30 hours in and I haven't even seen the final title set of the game. But what keeps me coming back to it is that almost every time I die, it's my fault. Spelunky rewards caution and harshly punishes hubris. While learning the ins and out of the game can be frustrating in the beginning (unless you fear spoilers, I might suggest watching a Let's Play of the game before you start just so you don't immediately get murdered), the feeling you get once you get the hang of the enemies and traps is great. By the time you feel start to feel overconfident, you make to the next world where the game humbles with new enemies and traps.
Tiki traps are still the bane of my existence, by the way.
The random generation of the levels keeps the game from feeling stale, even as you base your head against the same tile-set over and over again. As I mentioned before, the game keeps things mostly fair, though I have run into a map generated in such a way that if I didn't have bombs I could not continue, but this has only happened once or twice in 200+ runs. The traps and enemies are also mostly fair (outside of the occasional off-screen arrow trap that gets triggered before you can see it, and such).
So, seriously, if you have any stomach for rogue-like games, give Spelunky a try. Please. I could use some people new to the game so my score isn't consistantly at the bottom of the Daily Challenge anymore.