Contrary to Alec's (Technology Connections) comments on Bosch dishwashers, the system is far superior to American dishwashers, in my opinion!
Bosch machines use a filter to catch big waste, which means the biggest waste can be siphoned off and cleaned every 30 or so uses (~3 months) into the general waste. This big waste is not macerated and recirculated within the machine, which clogs pipes and adds dirt to dishes being rinsed. You should remove big waste from dishes before loading them; I think this is true of all dishwashers. And while pre-rinsing is a waste of time (why people still do this baffles me), you should make some effort to take the largest waste off the plates as the machines are not designed to remove these effectively.
The Bosch dishwashers (and many other European dishwashers) do support a cold pre-wash, by means of putting some detergent in the bottom of the tub. However, there is probably no need. The first thing the machine does is rinse the dishes with cold water. This cold water rinse is used to remove initial dirt and contamination from the dishes and a turbidity sensor then measures how dirty this pre-rinse water is. If it is dirtier, then the subsequent cycles are extended and the heat time is increased, which while not exactly the same as dosing the dishes with more detergent gives the detergent more time to work. This is then followed by the hot rinse cycle where hot water is used to remove detergent from the plates, and as part of the drying cycle the plates are made to get as hot as practical with the cold, insulated stainless steel tub acting to dry the plates. This is remarkably effective: no second heating element is used (only the water heater) and, unlike systems with that heating element, there is no risk of melting plastic plates, utensils etc., as they are not directly exposed to the element, but plates come out almost perfectly dry at least when the machine has been allowed to run overnight and is unloaded in the morning.
The machine is also very water-efficient, on its economy setting using only 6 litres of water in total, which is some 1/10th of what an average hand-washer uses.
I have never had any problem with the Finish tablets myself, and in the UK I can purchase 144 tablets (2x72pk) for about £12 including VAT, or around 9p/wash. The dishwasher itself uses 1.4kWh of electricity on the 'Intensive 70C' setting which at standard rates is ~2x the tablet cost; I however run the dishwasher whenever possible during my 5 hour off-peak period where electricity is 5.5p/kWh.
I have actually found poorer results from other tablets, but admittedly haven't tried powder detergents in this particular machine.