Gotcha. Well there are no side quests...a select few achievements listed could be counted as mini side quests, but honestly, there's not much to do after completing the game other than downloading the epilogue. (Which I am unsure of what content it contains because I have not purchased it yet, myself)
The story is pretty good. I started to appreciate it more towards the end, and then by the end, I was mixed but I liked it overall. There are also some extra details about the land, the characters, etc. that can only be learned through conversing with your partner character Elika. Interesting stuff.
Final veridct is yes, I would reccomend buying it. It's a fun platofrmer, nice story, small but interesting cast, and beautiful graphics. Plus, the price dropped to $30 so it's much more reasonable now. =)