My roommate works at VistaPrint, I wouldn't recommend them to ANYBODY. They employ shady tactics such as trimming a few millimeters off of each side of the card so they could fit an extra two or three in their printing presses (this also makes your card smaller than the general business card size).
Their quality is actually really shoddy as well, and the free cards all say "print at VistaPrint" on the back of them. Not to mention the fact that they go to all lengths with retention emails after you place a single order (without having the option to opt-out) to keep people ordering more. They also charge a ton of hidden fees.
In short: If you want your business card to be a serious reflection of your business, DON'T use VistaPrint.
I've used them 3 times in 3 different years, all business cards came out great, especially the foil ones. Much higher quality than ones I've had done at Kinkos and Staples. If they're not standard size, I definitely can't tell when comparing them to others.
Free cards do say that on the back, but they're free. What would you expect? They aren't meant for serious business use, for that you should pay like you would anywhere else (but less).
I haven't had any trouble with spam from them ever. And even if I did, it would be 2 clicks to just block their emails in the future.
Perhaps your roommate doesn't like his job and is not the best person to ask?
I've used them once and once was enough. The cards that I ordered were their premium variety but, when I received them, the card stock was poor and the cards were sloppily cut (meaning the bleeds looked poor). I would definitely pay more to use a more professional company.
You can really tell the difference between a vistaprint premium card and an overnightprints card. On the latter, the dots are tighter, the cardstock better, and the colors more accurate. For maybe a few bucks more you get less hassle and a better card.