It had too much crashes when it went open beta. It crashed the server between every map load, so all the players that came to test out the game left the same week.
Then whatever was left of the players left because the original devs went missing, and the newer devs (mainly yosh) started messing with the balancing, in a very cheap way.
Smoke grenades, emp grenades, anti-tank mines, mines can no longer be thrown and are planted as if you were planting a nuke, can't detonate remote as soon as you throw it, obelisk is weird af, etc...
At first it was very close to stock ren, now it is a totally different game, where the only similarity is the existence of teams called Nod and GDI.
The tactics are way different, infantry rule the game. Buying a tank is useless in maps that have tunnels. Big maps are very NOD sided, because GDI can never reach NOD (kind of like city where stanks win most public games). An old ren player, which should have advantage over these noobs playing on there, has no advantage at all since the game plays very differently.
We are working on a mod to address these issues. A developer from there agreed to help, and she already fixed like half of these issues. However the game is still built with UDK, so it "feels" different. The vehicles for example are a bit too realistic for ren players. Old ren vehicles run as if they were electric cars with no shock absobers... they just move where you point them
tbh I would encourage giving it a try after the mod is done. Even volcom agrees (though he hasnt spoken much on discord), but as I said in the moderators thread, we used to play it very competitively back when it still was close to old ren, and had tons of fun really.
I talked a bit about the negatives, but RenX does bring a lot of positives:
much better graphics. I get amazed at some of things I see there... the tunnels on Under look like a snow cavern; railgun tracer looks stunning, etc...
Spotting mechanism: point at something and press Q, and it will automatically do something like "enemy spotted at base entrance" and even highlight it on the map for your team...
no sniper hugging: there is no free-cam. you can still peek around corners with 3rd person, but you can't aim with free-aim
more maps. Some of the new maps are actually good, like goldrush and lakeside. Old maps are mostly kept untouched, with a bit of addressing to old issues. Mesa's harvy was moved from mid to sides + the cavern is bigger, for example. Otherwise, the map tactics are still the same really, and all the old tricks, like harv walking and ob jumping are still there, and done the same way almost
Missile locking is more straight forward, you aim, wait for lock, and shoot
modding tools are easier than ren, at least from my point of view. I remember ren's sdk need a sacrifice to compile
those are the ones that I can remember for now. But IMHO, if it was balanced exactly like ren is, it would be really good remake for ren.