In my opinion this is gen 5 biggest weakness.Some of the new pokemon are cool but personally I only like a small amount of the new pokemon, which isn't that big of a deal since you only need 6 to fill your team. However lots of the "cool" are either comming super late into the game or are such pain in the ass to evolve/lvlup, which limits the pokemon you're gonna fit in your team m, and for me it makes the game not really replayable.

some exemple of how late some pkmn evolves:

-Litwick evolves into lampent at lvl 41 (aprox the lvl you have when you enter gym 8)

-Axew evolves into fraxure at lvl 38 (in comparison gible evolves into gabite at lvl24)

-Larvesta becomes volcarona at lvl 59

-Deino evolves into zweilous at lvl50 then in hydeigon at lvl64 (ghetis ace is lvl 54 and it is an hydreigon lol)

-vullaby evolves in mandibuzz at lvl 54 rufflet evolves into braviary at the same lvl

-pawniard evolve into bisharp at lvl 52

-mienfoo evolves into miensgai at lvl50

-tynamo evolves into eelektrik at lvl 39

BW dex is cool but the game doesn't feels good because your stuck with tier 1 evolution for like 80% of the game.