Played a few more hours, done a big chunk of the marsh level, and continue to enjoy it. For all the complaints that this is just a nostalgia fest, I actually feel like they've added an awful lot of new play mechanics, eg. the switching between underwater walking and swimming - some of the puzzles here are quite creative and not something I've seen in other games.
However, I think in general the difficulty level is a bit too high, and this only emphasises how unrefined the controls are. For instance, the marsh boss, Trev (the northern bloke having a cup of tea while he watches the soaps - hilarious stuff). When it gets to the point where you have to wade around doing multiple jumps, it becomes very frustrating when you don't get the jump press timing exactly right. They should either tone down the difficulty, or make the controls a bit more forgiving and give some leeway on the timing. I think I spent an hour trying to beat that boss, and it seriously made me wonder whether the game was a worthwhile use of time as a result.
At the very least, offer varying difficulty levels, for those who don't want a crazy challenge. A lot of us, especially those who are BK fans and now adults with commitments, don't have as much time for games as it is. A challenge is good, but not to the point that it's frustrating and time-wasting.