The Gen 5 Pokémon are certainly creative. The problem I have with most of them are that they're too complicated: too many frills and patches of colour and all that. I believe appearance is the most important part of a Pokémon (with origin/inspiration at a middling second, and typing way down in third), and don't care at all for stats/battling potential.
To me (someone who began at Gen 1), Pokémon should be kept relatively simple. Plenty of the new Pokémon have so much detail it's hard to know where to look. I won't list any specific examples, but you know what I mean. I do have some exceptions to this (the Water/Rock turtle, Gigiasu (although that's not really complicated anyway), Kyuremu), but those are very few.
They should also look like they could be proper creatures. For one, that's why I take a dislike to Drifloon and Nosepass and other ones that are very much based on human features/inventions (I do like the Magnemite line, however, but I don't think nostalgia is the reason why). That's why I dislike the bin bag, the Poké Ball mushroom, the girder-wielding generic humanoid, the sarcophagus (its prevo could have been good, though), the ice-cream (mostly - it could still be feasibly natural, but I still dislike it for other reasons), the gladiator bug, the gears, and the candle/lamp (I kinda like the chandelier, though, because it's not overly obvious it's just a living object). And frankly, that's a lot of Pokémon for one Gen.
Most of the many humanoid Pokémon in this latest generation don't sit well with me either. I know we've had plenty of humanoids before (Alakazam, Gardevoir, Machamp, etc.), but they mostly still look like creatures rather than being some red guy with a large forehead in a karate outfit. I'll accept Gochurizeru as a gimmick (goth-loli, of course), but Meloia is just wrong.
Finally, the final evolutions of a couple of the Pokémon are just too different to be acceptable. A perfect example is Mijumaru turning into something almost completely different. Now, I do like the design of its final evo, but I don't think it should be related to Mijumaru. Desukan (the sarcophagus) is pretty much another example, as could be Ononokusu (the tusk dragon), but both of those have a few similarities to their prevos. Most of the bugs also qualify, but Bug Pokémon do tend to change a whole lot anyway. Overall, there are only a few examples of this, but it still contributes.
Liking or disliking Pokémon is, of course, an entirely personal thing. For instance, I like the legendary fighting trio (although perhaps not their types), the spiky Grass/Steel flailey thing, Burunkeru, Abagoora), and I dislike most of the bugs (for being too weird) and Koromori (a big NO! to the heart). That's just my opinion, though, and everyone will be different for their own reasons.
On the other hand, there are Pokémon pretty much everyone will dislike (the Gears, that Electric/Ground flat fish thing, the karate oni, the ice-cream, and whatever Furiijio is (seriously, what is it?). But that's just how it is.
The point is that there's plenty of creativity still floating around. The problem is with how it is used (too much detail, un"realistic" designs, etc.).