Well, I just doing review again, because it's been many patch/upgrade, along 2 DLC, and even Custom gamestart 4.10 version.
Game is every enjoyment and fun for those who forced on combat and station builder, but might not every enjoyment for non combat trader personal, as X3 is better for personal traders, autotrader and fleet manager while X4 is better for auto miner/gas, station builder, small fighter had chance to beat bigger but bigger ship in x3 is better. Weapons is not same as X3.
Fleet manage is remain more of similar but had other type issues.
X3 is great for slow ship, thankful to jumpdrive, but X4 do not had jumpdrive, it's not good for slow ship to be in, because once you under fire of enemies, you are unable to flee it.
X4 flavor of speed, speed is petty much had as you can flee or control battle whatever you think or feel best, but X3 don't care about slow ship, due jumpdrive, you can jumpdrive to save ship and yourself from game over screen.
Game is Fun and worth to buy, but X3 and X4 game is not same, just similar but difference gameplay due economics, way ship's speed (x4)/jumpdrive(x3) importance change and auto trader is great in x3 but you can't had that (I'm not sure they removed it or nerfed by need high level star pilot to do that in x4 but auto miner replaced auto trader from x3 to x4, x3 had mining station endless, depend output to keep up, but x4 don't had any mining station endless . Raw resource could ran out and it's take some time to regen in sector in x4.
So x3 is little slow while x4 is more faster, but both are still same, it's take a while to make credit to build or buy ship, so go on, couple real day at least to start up for station, it's lot of credit and time to set up station and making profit that way.
It's had fewer bug since 4.10 than game come out. And more story Plot that gave you choice as well.