For people who played previous versions;
The graphic improvements are noticeable, but not drastic or jarring, the original charm is retained.
Original voices (50% of what made me love this game as a child) are still there.
The controls feel good, but unit patching is a bit hit & miss, AI are even more hit & miss.

The new content in the form of two short campaigns was... okay? Not terrible, just not very in depth.
One mission requires hitting several objectives quickly as regular 'easy' attacks from various signposts will be followed by one that will be very difficult to survive - even on the lower difficulties, and impossible if you weren't prepared for it (I wasn't, and I'm not sure the game really warns you about this well enough)
The two campaigns focus on the Rat & Snake's counties, but with much stronger unit comps than they seem to have in the original campaign. New intros & voice acting supports the new content.

Multiplayer as a built-in is nice, can be iffy with connectivity (Still easier than the old way), but lots of player made maps and a couple of updates have improved it so far.

For people who haven't played previous versions;
If this is your first Stronghold game, this version is probably the best option as it's a little easier to play.
Stronghold Crusader is often referenced as a better game - largely because the AI can build their own castles, which they CAN NOT in this game. The strength of Stronghold is the narrative campaign - which Crusader doesn't have.
A series of well sculpted missions with excellent writing & voice acting in their intros. The military campaign starts of easy and learning, introducing new elements, weapons and units in line with the story progression.

It hasn't aged perfectly as a game, but I feel the main campaign holds up very well, even after years of re-playing, I didn't skip the intros, and thoroughly enjoyed them.

The economic campaign sucks, but individual 'Invasions' and Economic maps are pretty fun, the sieges are cool, especially if you're familiar with the castles.

Many players of the original are disgruntled that this version hasn't imported features from Crusader, but that doesn't make sense to me personally, I got more or less what I expected, a polished, more playable (and OBS capture) version of the game from my childhood.

I do love Crusader, the skirmish missions, mercenaries and variety of AI lords, but can only hope that the success of, and support for Stronghold DE will lead to Crusader DE in the future.