This microwave was advertised as a direct push-in replacement for my Bosch HMT8656 which died suddenly aged 5½. The front surround is indeed the same size but the roof of the oven has been fitted with a duct which, I imagine, is designed to vent the steam through the gap between the top of the door and the surround. This means that the vertical clearance needed to get the oven into the housing is slightly increased and in my case necessitated a bit of carpentry.
The oven capacity is larger than its predecessor and it has more programmability. Functionally it is perfectly Ok; it cooks and heats food and liquids as well as any microwave. Unfortunately for me however, it sits in the same housing as and directly adjacent to a Bosch double conventional oven which it supposedly matches but one glance reveals the inferior quality of appearance and finish. The front surround of its predecessor was all metal and felt robust whereas the new one is plastic covered with a veneer of metal; it feels flimsy and looks cheap. The door on the HMT8656 closed with a discreet 'clunk' but this one has a tinny 'clack'. The mechanism also is more noisy overall. Bosch have gone down-market here which is a pity because they are still charging up-market prices.