Most of HP Ink (pun intended, remember that the HP of Yore split into HP Enterprise for Big Iron and Services, and HP Inc for desktops and Printers, tickers: HPE and HPI) Laser printers, even from the begining of "Laser Time" time, use laser printing Engines from other manufacturers (In the begining, mostly Canon, nowadays, they use Samsumg Engines too). So HP gets the Laser engine from a 3rd party, slaps a Microcontroller, some plastic, writes a bloated driver, and of you go.
Samsung and Canon, on the other hand, do all that, but also make the laser engines...
Also, HP Ink is not Strong in Multifunctional Lasers for SOHO/Prosumer/Office/BigCorporates. And has no presence Whatsoever in the Copier business.
For HP this deal means:
1.) Get rid of a competitor, actually, they probably got Samsung because it was the weaker of the lot, or for the other reasons detailed here. No worries, we still have Brother, Lexmark, Canon, Xerox, ... even Dell
2.) Verticaly integrate the Laser Engine into the production, with the associate cost savings. Sorry for Canon, no more HP bussiness for them in the medium term... (contracts will not be renewed, or renewed in shorter terms than without this deal, new products will be based mostly on Samsung Laser tech).
3.) In the medium term, deny other competitors (Dell, for example) of Said engines (Dell uses Samsung laser engines on many of their house brand lasers printers) or, having competitors using their engines to actually put money on HP's Pocket. Again, most likely contracts will not be renewed, or will be renewed on shorter and/or more expensive terms. If I were Dell, I'd rush to Canon's HQ and invite them some niguiri and Sake to, you know, discuss things.
4.) While the product overlap is Huuuuuge, the Market overlap is not, both Geographicaly (think, for example APAC, not only US) and client wise (enterprise vs consumer vs prosumer/soho). That means that HP Ink printers can reach places were samsung is strong, and Samsung printers can reach places where HP Ink is strong.
5.) Cross selling (Mr 500 employee office, here are your printers, can I interest you in some workstations/desktops/laptops? Mr. 800 employee office, here are your Workstations/desktops/Laptops, can I interest you in some printers to go with them?)
6.) "Cost saving synergies" (i.e Layoffs/Pinkslips/Redundancies).
7.) A nice throve of patents with which to defend from (don't even think on suing me, I have my patent's and Samsung's), or harass (hey, Sign this cross-pattent agreement with me, or we'll sue), or even get royalties money from competitors.
8.) Get a presence in the copier business.
Now, is that worth $1.05*109?
Only time will tell.