@ SRanger
The true ending is the same ending the anime took.
In total there's 5 routes + the true end.
All of them have it where Okabe stays with that person and doesn't cancel out the D-mail they sent.
There's also two bad ends you can get
The first of which is triggered after repeating a certain scene though from my understanding it's random when it happens. The second is just picking the only other choice present at the scene it happens in.
Each route is about an hour tacked on to the chp it takes place in give or take. I completed everything but the two bad ends in a total of about 20 hours, but I sat down and read non-stop in 3 hour chunks.