Pierre-Emerick Aubameyang - Borussia Dortmund to Arsenal (£55.4m)
Arsenal have signed one of the best goalscorers in European football and ultimately it's what happens on the pitch that counts. Alexandre Lacazette's goalscoring has tailed off, not helped by the wider dysfunction throughout the team, but there is a feeling he struggles to absorb the physical demands of a full season as lone striker.
The Frenchman's touch and link-up play has impressed, but he is not as fast as many imagined and Aubameyang will stretch defences and offer more counter-attacking potency. One of the reasons the limited Theo Walcott lasted so long at Arsenal is that pace in the final third is essential for their football to function.
Virgil van Dijk - Southampton to Liverpool (£75m)
The most expensive Premier League purchase of the January window was completed on New Year's Day, as Liverpool landed the high-class centre back they were chasing all summer.
Few would deny Liverpool overpaid for the Dutch defender, perhaps to smooth things over with Southampton who they angered with their public courtship of the player, but he is a significant upgrade on their previous options. Comfortable in possession, van Dijk also has the mobility to cope in isolation which is critical given the aggressive defensive strategy employed by Klopp. The former Celtic man also gives Liverpool added presence in both penalty boxes particularly at set-pieces.
Olivier Giroud - Arsenal to Chelsea (£19m)
An emotional one for Arsenal fans, who were sad to see the player who bore the brunt of their anger for so many seasons leave. His late goals from the bench saw him gain something approaching cult hero status at the Emirates, and Chelsea have undoubtedly acquired one of the best 'Plan B' forwards in the division. Selling to their London rivals might have been necessary evil to push the Pierre-Emerick Aubameyang deal over the line, but seeing Giroud in a Chelsea shirt could sting.
Antonio Conte never fully trusted previous deputy Michy Batshuayi and has had precious few attacking options to change the course of a match. Giroud will not transform Chelsea's fortunes, but expect him to salvage a few points for them with late goals.
Alexis Sanchez to Manchester United/Henrikh Mkhitaryan to Arsenal
Who got the better of the deal? That is the question you will hear repeatedly over the next few months, and plenty of tedious social media one-upmanship between both sets of fans. Put simply, Man Utd have the better player. Alexis Sanchez was involved in nearly a third of Arsenal's goals since the 2014/15 season, scored 30 and provided 15 assists last season and is world-class talent capable of playing in all attacking positions.
Philippe Coutinho - Liverpool to Barcelona (£142m)
A deal that divides opinion among Liverpool fans, with some arguing the club should have kept Coutinho to ensure Champions League qualification while for others the astronomical transfer fee was irresistible.
For Barcelona, it is an expensive step towards replacing Neymar though as a creative midfielder player who likes to start from the left and dribble, Coutinho could prove a capable heir to Andres Iniesta.
Ross Barkley - Everton to Chelsea (£15m)
Sent to Coventry by Ronald Koeman and sidelined for months through injury, Barkley has a chance for a fresh start after things turned sour at Everton. At £15 million, this is a gamble Chelsea can afford to take and Barkley has enough talent to ensure there could be a significant upside.
The challenge for Barkley is to define the type of player he is: a goalscoring No.10 judged on his end product or a central midfielder who starts moves with driving runs from deep? His decision making must improve and future managers will address his tendency to take too many touches.
Daniel Sturridge - Liverpool to West Brom (loan)
Relegation-threatened clubs always look for a goalscorer in January, and it is hard to recall a club in West Brom's position signing a player of Sturridge's calibre. Sturridge has a wide variety of finishes in his locker and quick feet in tight spaces. Can be he the special one for West this season?
Theo Walcott - Arsenal to Everton (£20m)
The former Arsenal man has continued to under-achieve at Goodison Park, with two goals and an assist in his first two league starts...
Everton desperately required some pace and goal-threat in a squad over-populated by attacking midfielders and No.10s. Fans are well aware of Walcott's limitations by now: he has no left foot, struggles to play with his back to goal and possesses no tricks to dribble past a full-back from a standing start. There are two skills he brings to the table: the quality of his off-the-ball movement behind defences and his finishing, and he has made a career by truly excelling in these narrow parameters.
Aymeric Laporte - Athletic Bilbao to Manchester City (£57m)
Pep Guardiola can longer rely on the fitness of Vincent Kompany, Eliaquim Mangala was deemed surplus to requirements while John Stones has been error-prone since his return from injury. So Man City reached for the cheque-book and signed highly-regarded French centre-back Laporte who looks an ideal fit for a Guardiola team.
At six-foot three, the former Bilbao man will bring mobility and physical presence to the City back-line. As a natural left-footer he will balance the back half of City's team and give them more angles and avenues to build-up from the goalkeeper. The transfer fee is hefty, but at 23 he could be City's centre back for the next decade if the move works as well as all parties hope.
Lucas Moura - Paris Saint-Germain to Tottenham Hotspur (£25m)
Spurs have dropped points against Burnley, Swansea, West Brom and West Ham at Wembley this season, struggling to break down deep-lying defences in each of those draws. The signing of Brazilian winger Lucas Moura is intended to give Tottenham's attack more speed and unpredictability in these types of fixture.
Mauricio Pochettino's team are built upon organisation and collective strength rather than the quality of individual parts. However, when teams sit back and ask them to create they can look a little bit too organised, co-ordinated and rehearsed. It risks becoming a little predictable, and Moura is a player who will bring intuition and the ability to produce something from nothing.
Which Premier League club do you think that did the best business in the January transfer window? Tell me in the comments.