I've been using the EC for a short while now since I came back to EA UO and I've no idea why anyone would turn on the legacy containers option, particularly legacy containers + grid view. Just a waste of screen real estate. =P
The default EC container grids, the decent map and hotbars are big draws for me as are simple things like right clicking items on corpses to loot them, ability to block click actions on your character to prevent accidental dismounts, having to hit enter to chat to free up all keys for macros without spamming a load of nonsense when speaking, improved lore windows, etc. It's these tiny tweaks which make general gameplay suck less as these are the sorts of features I've grown accustomed to in clients of more modern games and it's great to see them in UO.
That said, the client fails at so much too which is generally due to developmental neglect. There's still outstanding bugs with functionality as fundamental as health bars not being updated which is just lame; basic functionality like this should always be operational and if it is not it should be fixed in an emergency patch. Can you imagine if health bars stopped updating randomly in the WoW client forcing you to relog? There would be an uproar and it'd be patched within an hour most probably.
Additionally there are still client crashes which occur for reasons as trivial as scrolling through the map which, again, is fundamental stuff and there's no excuses for any crash to still exist after years of supposed development. Crafting also totally sucks and the macro system is exceptionally limited in regards to what you can achieve when training any crafting skill. I'd have thought one of the basic goals of the EC was to replicate everything the CC + UOAssist could do and that's certainly not the case when it comes to handling crafting menus, etc.
In regards to the whole graphics debate ... meh. The whole argument is boring, tbh. I don't play UO for its graphics and I don't know anyone who does. The CC's graphics suck and the EC's graphics are pretty much the same as the CCs + some modified mobs. Neither are good and most people are arguing one way or the other just because that's what they're used to. I was used to the CC graphics and the EC mobs looked weird to me, but I just overlooked this and now I've got used to the latter. I logged in to the CC earlier for the first time in ages and was surprised just how lame my miner's fire beetle looked compared to that massive thing in the EC, lol!
Anyhoo, overall the small improvements in the EC currently outweigh the handful of issues which exist for me which is why I use it, but a compromise is definitely needed to do so and that shouldn't really be the case. The EC is decent and with a bug squashing drive to shore up the fundamental functionality of it then it would be a more credible choice for those looking for something stable.
Btw it sucks, on either client, that in 2012 we still have to logout completely and log back in merely to switch characters. That's probably what is annoying me the most right now since I'm so used to pretty much every other game allowing you the option to drop back to the character selection screen. Ho hum. Maybe that's something to put to the devs in the next ask and answer or whatever, cuz I'm pretty sure I can't be the only one who hates that!