You can't log back in to print out your taxes if you need to in the future. I logged back in to print after buying a new printer cartridge, buy not all of my forms were available... most importantly the 1040 ez. This made my life miserable when I went to apply for my student loans. I emailed their customer service "tax questions" area over and over again until my forms magically showed back up after about 15 complaints. They never emailed me back or called to apologize or acknowledge that they were at fault.
After reading other's complaints online, I decided the next year to try to login to see if I could access my forms since I now suspected the site to be a scam. I typed in my social security number and password. The system didn't recognize my information, which I thought was weird since I just filed the year before. Then somehow after navigating here and there on the site I was able to find the files to print. Very strange. All I can say is that the website isn't put together that great and doesn't have a logical flow.