I am sure McLaren thought it would be a good move in the long run but in the meantime it's just downright embarrassing and it's shocking to see what used to be a top team at the back of the grid and struggling to even finish a race. This years engine seems to be even worse than last year.
It was and probably still is a good move for McLaren. Yes, it's embarrassing for a team with az rich f1 history as McLaren to have these reliability failures and power deficit to Mercedes, Ferrari and Renault but the logic behind the switch is sound....the likelihood of a customer team beating a works team is slim to non-existent and they had to do something to change those odds.
Honda completely redesigned the engine from last year to adopt the same layout as Mercedes and yes, right now it isn't as good as last years but this engine will allow for better development now they have dumped their "Size Zero" approach. Another thing to remember is Honda is still two years or so behind the rest of the field in creating and developing these hybrid engines.
Ferrari are unlikely to sanction another deal using year old engines. The reason Sauber are running year old engines is Ferrari wanted a three year deal, something Sauber were unwilling to agree to. The Honda deal makes sense as they're likely cheaper than Ferrari and Honda may actually listen to them as a partner rather than simply as a third thought customer.
It will be interesting to see how Sauber will be treated as I'm sure they are referred to as a Customer in the press release. McLaren have always been Honda's exclusive partner since their return, if McLaren keep Honda after this year I'm wondering if McLaren will adopt the status of Honda's Works Team and receive preferential treatment over Sauber e.g. first to receive and run upgrades etc.