We've been playing TDE 5 for the last year and a half and it's gone pretty well. We even enjoyed the character creation. That runs more like GURPS where you have points allocated and you can build whatever you like. Invariably, someone builds the rogue, the wizard, etc. but there's a lot more flexibility there.
The skills with the 3d20's really aren't so bad. I like the fact that it yields a Quality Level that allows me, as the GM, to bake in some, "You get it done, but there's this small (or large) consequence as a result." Sort of like the FFG Star Wars dice. That part actually flows pretty quickly.
Combat, as has been said, is a bit of a different animal and does tend to run slower. The spells, which I feel are kind of limited and underpowered, take a while to cast, but this actually creates decent balance between the casters and the martial types.
I like the armor soak, the chance to parry/dodge an attack, but it does get fiddly. Conceptually I really like those things but in practice it tends to slow things down. And nobody likes rolling high for a "hit" only to have their enemy deflect what was going to be a powered-up hit. So I've pretty much stopped giving that power to the baddies and just given them more hit points (as my own house rule).
TDE is a little different conceptually, as well. If your group likes fighting monsters you'll find that this game is really more focused on using your character skills to solve problems, investigate, etc. That's why you can literally roll up a chocolcatier, a dike engineer, a farmer, etc. Everyone brings their various skills together to do stuff. The VERY small and limited bestiary makes it plain that this game really isn't all about the hack and slash. My group was raised on D&D and Pathfinder, so I've converted a few monsters and brought those in and everyone seems to be having a good time.
I will say that I feel like the pantheon is a little uninspired. More could have been done with it, for sure, but it's serviceable. What I most dislike about it is that there's really only one "bad guy god" and a dozen demons running around. I like having a broader base of bad guys at work so there are competing agendas, etc.
Final thought as this may be an important decision point. A few years back they came in with Paizo's help, had a big kickstarter, and came in like gangbusters trying to really penetrate the American and English-speaking market. This game's origin is in Germany and it's apparently HUGE there. Over the next several years they had a Magic kickstarter and Gods kickstarter and I supported everything to the hilt, buying anything and everything they translated to English to show support, etc. Their presence and effort in the English segment has dropped off steeply over the last year. They lost Robert Adducci who kept their online presence going pretty well as their Community Manager and whoever they replaced him with must be in the witness protection program. All communication has evaporated. No new kickstarters or translations have been announced (and previously they had a few queued up). I asked the question point blank in their Discord server back on 9/21 - Do they have anything else coming out anytime soon and I've gotten crickets, even after a number of other people piped up and said, "Yeah, this!" So if you prefer to play a game that is actively supported, I've got a bad feeling about the future of TDE.
There is enough out there in the Core Rules, Aventuria Compendium, and Magic book to play a well-rounded game, no doubt. But I think they may be re-thinking their commitment to the English-speaking market.
Hope that helps. I can offer nothing on WFRP 4 as I've never played it, but if you have further questions on TDE I'd be happy to help. I've said it a couple of times but I'll repeat it once more: my group is having a great time with it, so that's all that really matter to me.