Today is your last chance to upgrade to Windows 10 for free, but you might want to think twice before clicking the install button. The offer is a great — after today, the software will jump to more than $100 — but digital privacy advocates still say Microsofts latest-and-greatest software has some pretty serious flaws.

First, some good news: from a basic user’s standpoint, Windows 10 is a return to form. It’s not as confusing as Windows 8, which featured an interface that had little in common with every other version of Windows that came before it, and it also has a bunch of features to make life easier for everyone who decides to give it a whirl.

Windows 10 also fixed several long-running security vulnerabilities and will continue to receive updates after its predecessors have been abandoned. Choosing to use Windows 10 will make your data safer than previous versions.

Microsoft has also pushed to make Xbox One games available on Windows 10, removing itself from the console wars. Being able to play your games on multiple devices is a nice bonus for anyone who owns an Xbox One and gives Windows 10 a shot.

Unfortunately, there are some serious privacy issues you should think about before installing Windows 10. That’s been true since it launched, and several groups don’t think Microsoft has done enough to address the problems. On July 11 France’s privacy watchdog told Microsoft to basically stop ignoring Windows 10’s problems, which might not be immediately apparent to some users.

Microsoft knows too much about the software people use

Windows 10 collects information about the apps people use so Microsoft can identify problems and promptly fix them. France’s Chair of the National Data Protection Commission (CNIL) says that Microsoft collects too much data with this feature. According to CNIL, Microsoft knows exactly what’s installed on a device and how long it’s been used, giving the company an idea of what software is popular with its users.

Microsoft installs advertising cookies without user consent

Windows 10 also uses advertising cookies “without properly informing [consumers] of this in advance or enabling them to oppose this,” CNIL says. People have to choose between using Windows 10 — and therefore offering up their data to inform ads — and sticking with an old operating system to maintain their privacy. And, worse, most people don’t realize they’re making that choice.

Microsoft doesn’t secure accounts very well

Windows 10 users are able to set four-digit PINs to provide easy access to their Microsoft accounts. Great! Convenience is always nice … except for when a company doesn’t limit the number of guesses someone can make on that PIN, thus allowing them to brute force their way into the account. CNIL warns that this particular vulnerability means that “user data is not secure or confidential.”

It’s a waiting game either way

CNIL ordered Microsoft to address the issues within the next three months. By then, the free offer will have expired, which means anyone who hasn’t yet upgraded has a choice: Download now and pay with their privacy; or download later and pay with their hard-earned cash. It all comes down to which is more important to consumers.

Photos via Getty Images / Andrew Burton