The Heather is small but powerfull. The silicon cup are oftenly failing and let heating unit sink. Fortunately is well sealed.
The controller is ok, mine is keeping the tank temperature between 25 to 25.6 C. Has two plugs - may be usefull.
The temperature senzor is well protected (Sealed) and is kept fully submersed.

Overall i rate it as a good product and excelent for its cost

So far so good
Only a month or so working but looks good as it keep temperature almost accurate

very good heating my 600l fishtank with no problems

Very good Heater with digital Control.
all in one
is good for 1000l