Gwent has been in beta for a while and the players produced a ton of feedback to the devs to improve it. The guys at CD Projekt Red apparently take this feedback by heart, considering that the effort they put to keep this very peculiar CCG balanced. With the latest patch, they also demonstrate that they are not afraid to take risks, introducing a change that adds a whole new strategic layer to Gwent: relative positioning.
Whoever played Gwent (either the standalone version or the minigame in The Witcher 3) knows all too well that the key to victory lies in the positioning of your units on the board. Until this patch, players could place their units on the melee, ranged and siege lanes, depending on the unit played, and it didn't matter where on the lane the unit is placed relative to other cards. With this update, you'll be able to choose, upon placing a card, in what position on the lane you want to place your unit.
This adds a new layer of strategy because, as of the last update, many cards have been changed to take advantage of the new system. For example, Commander's Horn now doesn't affect the entire lane but only up to 5 adjacent units in it. A similar change has been applied to many other cards of all the factions, including Thunderbolt Potion, Manticore Venom and even to the power of certain heroes like Radovid. This change could make the game much more interesting, opening new strategic options while limiting the power of the cards that affect multiple units.
There are other interesting changes in this patch. For one, the board received a graphical revamp, in order to make it more legible and accessible. The update also introduced a move history feature that allows players to see what cards have been played up to that moment. A sorely missed feature in previous versions of the game. It also added a new taunt system that allows players to communicate using pre-set phrases spoken by their avatars, the way it works in other virtual CCGs like Hearthstone.
There also are many balance changes to cards included in the patch, too many to be listed here. Let's just say that, even ignoring the cards that have been updated to take advantage of the new positioning system, some of the changes are pretty impactful. For example, the Monster faction ability has been changed to affect only cards played from the player hands and the unit spawned by Eredin's power. Numerous other changes are significantly changing things up in the game as cards get new abilities, or entirely rebalanced. For more detailed info, you can find all the changes here.