Having now frequented One World for 10 years, I know for certain what I like and dislike about this staple of Baltimore veg dining.
I will start with what I like, since many people will probably stop reading after that (or so say certain scientific studies that I am presently unable to cite).
A few years ago One World greatly improved the quality of their dinner specials, and began including a lot more vegan options. I greatly appreciated that, and the primary reason I keep coming back to One World is for their vegan dinner specials.
One World is also a good place to take visiting family, who often represent a mix of dietary habits. Their menu is very balanced in terms of flavors and cuisine types, so usually everyone can find something to eat. That is a good thing.
Now the things that I don't like...
One World's dining room reminds me of eating in a school cafeteria. When it's more than a few tables full, it turns into a cacophonous vortex of swirling noise, over which it's near impossible to carry on a conversation. Given that JHU is right across the street, this happens pretty much nightly. Sitting at a table in the bar area is actually quieter, ironically so, as you are right next to the bar itself and the televisions looming over it. Go figure. But do keep this in mind if you want a quieter dinner. You can always sit there and the bartender will take your dinner order.
A second issue that has arisen recently is that the vegan desserts have taken a turn for the worse. An acquaintance of mine used to bake for One World and her desserts were out of this world. There was a long period of time where I would go to One World primarily for the varied dessert experiences, long after I'd grown bored with the regular food menu. But now I won't even order dessert, which is absurd considering how much I love it. Every vegan cake there tastes the same now: dense and lacking in flavor with sickly sweet frosting. Unlike in the past, there are rarely other vegan options, although I will note that the fruit tarts are pretty decent.
Service can also be spotty. They had a good solid wait staff for a couple of years, but those people all left. Since then it's been hit or miss.
I hate to be hard on any vegetarian restaurant and perhaps some of my complaints about One World are simply due to having eaten there too many times. But I also think I want more from a restaurant than what they have to offer. It's 2015 and the old menu standards no longer cut it.
Cons: noisy, vegan desserts are hit or miss, spotty service