Yes, exult is a great modification, as it enhances perfomance, works very stable, gives you many possibilities to refine the graphics with filters (although you can do that with taewoong's custom dosbox too), it lets you change the resolution and irons out many bugs. The keyring mod gives you a small, but enjoyable questline. Some other things have been changed (like the altars of the virtues), there are more ways to interact with the world (you can make butter) and it's an overall good and comfortable way to play the game today.
There is a caveat however: Some things of the original Ultima VII don't work as they should under Exult: the broken lighting-system for example, but also some other "details" like npc-reactions or npc-schedules (the smith's schedule in Minoc for example). Some will see that as unimportant details, but for me personally, Ultima VII lives exactly of such environmental details.
