I do not own a maltipoo, but I think one of the first things you should know about this designer dog is that many, many, far too many "breeders" of them are disreputable. They are common puppy mill breeds. You will likely very easily be able to find a puppy, but finding a breeder that actually cares about the quality of the puppies is going to be hard. Many of these breeders are absolutely excellent at disguising their operation as reputable.
That being said, I do know a few alleged maltipoos, and they're kind of all over the place. A co-worker's is nice enough but barks at absolutely everything. Another is a complete couch potato. Another is hyper and fairly destructive, but is around 2 years old, so not unusual. The first two came from a "breeder", and the last was obtained from a shelter. So...take that as you will, but know maltipoos are technically a mixed breed and it is more difficult to predict both their personality and appearance.
Why buy a mix? You can get either breed from a reputable breeder (I would hope!!). Both breeds require grooming and regular hair cuts and care with the Maltese needing daily care (brushing) due to the silky nature of the coat. Poodles need clipping (we did ours once a month.. clipped close all over as a "kennel Clip." Bichon's are also nice dogs that also require coat care.
While I believe each to his own, I have never understood the desire to pay large money for a designer dog when the root breeds are established and are often represented by reputable breeders that have run genetic health tests on the parent dogs.
One place I recommend looking is Good Dog Good Dog: Find the Dog of Your Dreams from Good Breeders and Shelters It's far from perfect, and you will still need to do your homework, but they do have minimum requirements breeders need to meet before being listed. I also recommend checking the OFA website https://www.ofa.org/ to see what health testing each breed needs to have done (and verify that a given dog has been tested) I know Poodles have several issues that should be tested for, I'm not a familiar with Maltese, but 'm guessing they need at least a patella rating.
As 3GSD mentioned, Poodles and Maltese have very different coats, so grooming can be pretty extensive, depending on what type, or mix of types, they inherit. You will need to do at least weekly grooming (brushing and combing), and be prepared to either pay for professional grooming every 6 to 8 weeks, or else learn to clip them yourself.