Having only recently played it, I have to say the game is a great entry into the Pokemon series. Does it live up to the standard of the previous games? Well, yes and no. I'll start with the pros because they are plentiful.
As a whole, the new Pokemon introduced are creatively designed, although some are more memorable than others. While many complain that there were not as many introduced here compared to previous generations) I think it works as it does not alienate those new to the series (learning about all 700+ Pokemon sounds like a daunting task to me). Next, the main focus of the games: battling. With minor tweaks, it is pretty much the same as in previous games which is not a bad thing at all. The most notable additions of Fairy typed Pokemon and Mega Evolution are enough to spice up the formula. Fairy helps balance battling with its resistance to Dragon type, encouraging more variation in online teams (not everyone carries their Garchomp or Hydreigon into battle anymore). Mega Evolution gives a new lease of life to Pokemon who often were often forgotten, as well as to fan favourites such as Charizard and Mewtwo. The soundtrack is arguably one of the best in the series so far, making even a wild encounter with a Pidgey feel epic. Being able to move diagonally in the over-world was indescribably satisfying and the layout of Kalos was perfect for highlighting the varied setting within the game.
However, I do have problems with this game. For a game that is on the 3DS it does not utilise the 3D nearly enough, and when it is on during battles the frame-rate drops horribly low (looking at you Mega Evolution). It might just be personal but this kills off some of the immersion for me. There is also a distinct lack of post game content when compared to previous games, aside from the Battle Maison and a few other small tasks which removes some of the replayability, Another nitpick with the game is the "friends". Unlike previous rivals who encourage you to get better, antagonise you or have some kind of interesting connections to the plot, these new rivals are just there. They never feel like a threat and I could never see them as a challenge I, the player, must rise to.
My final complaint is one that I see argued about everywhere: "these new games are too easy". Compared to previous games in the series, there is little to no challenge here. The gym leaders are generally very easy to beat and the Elite Four only have four Pokemon each. I understand these games are designed for all ages, they have to be somewhat easy for those new to the series, mainly children. The thing is, the previous games were aimed towards children as well and I can still return to those and find some degree of challenge, whether it is Lance's Dragonite or Flannery's Torkoal (I am quite positive I am in a minority who always struggle with the latter). Although it was a hassle to unlock, Black 2 and White 2 each had a Hard mode built in for those who fancied a challenge, something I would appreciate as a Pokemon veteran.
Overall, the game is a good entry to the long running franchise. It will be interesting to see what lies in the future for the main series Pokemon games. At time of writing there have not been any main series games since Omega Ruby and Alpha Sapphire in November 2014, nor has there been any "generation 7" or "Z" announcements. I am positive that whatever is in store for us fans over the next few years will be phenomenal.