Yeah, you should definitely pick this one up, especially if you've never played a Pokemon game before.
However, this isn't challenging at all. The most challenging part in any Pokemon game was back in the Red/Blue days, where as soon as you picked your Pokemon you had to fight your rival. That was tough, and totally up to chance. If your rival happened to do all attacking moves that time, you lost, but if he decided to do some stat-changing moves, you had a pretty good chance of winning. I remember turning my GB on and off so that I could beat him and get that free level. Now you can level up before fighting your rival for the first time. In Ruby, by the time I fought my rival, my Torchic was already at level 10. Sure, they upped the ante on the Elite Five (making the Pokemon higher levels), but a few runs through Victory Road just leveling up and they're no problem.
To sum it all up, if you're looking for a challenging game, this is definitely not it. However, Pokemon is addicting, fun, and has the biggest replay value of any game I've ever played (once you've done everything, you can work on making the "perfect" team, catching every Pokemon avaliable, and leveling up your "perfect" team to level 100).