There's something refreshing about T-Mobile’s new “un-carrier” strategy. The struggling No. 4 player in the U.S. wireless market has decided to ditch contracts altogether while separating the cost of the device from its new Simple Choice rate plans. Overall, consumers can save quite a bit of money versus AT&T, Sprint and Verizon. However, T-Mobile's plans aren't simple and straightforward as you might think, and there are plenty of caveats for every perk. Here’s a closer look at what subscribers are really getting — and what they’re not.

  • 1White Lie No. 1: You’ll Save Over $1,000 versus AT&T!

    If you trust T-Mobile’s marketing department, you’ll save more than a grand versus AT&T by opting for one of its Simple Choice Plans. But if you make comparisons based on what plans most people opt for on AT&T, the savings aren’t as great.Let’s say you signed up for 2.5GB of data on T-Mobile for an iPhone 5. The phone costs $99 up front and $20 per month for the device for 24 months, plus $70 per month for unlimited data. Total after two years: $2,259. A similar AT&T Mobile Share plan with 4GB of data costs $110 per month when you add in the device access fee. That comes out to $2,839, or a savings of $580, which is significant but not mind-blowing.

  • 2White Lie No. 2: No More Commitments!

    T-Mobile says you “don’t have to serve a two-year sentence to get a new phone.” That’s true, but most consumers will wind up signing up for a 24-month payment plan, which is the same length of time as other carriers’ contract plans. The good news is that once you pay up the phone is yours, and you can upgrade to a new handset at any time. Plus, T-Mobile will let you trade in your old handset for “fair market credit.”MORE: Should America Ditch Subsidized Phones?

  • 3White Lie No. 3: It’s Unlimited Data!

    It sounds too good to be true. The new base $50 plan for T-Mobile is unlimited, but it only includes 500MB of high-speed data. After that you drop down to pitiful 2G speeds. T-Mobile’s Unlimited Nationwide 4G Plan includes unlimited 4G data but you'll get throttled after 5GB. This top-tier plan also doesn’t include mobile hotspot functionality, which AT&T and Verizon include at no extra charge with their shared plans. In fact, you get only 500MB of data for mobile spot usage on T-Mobile’s unlimited plan. An additional 2GB of hotspot service costs $10 per month.

  • 4White Lie No. 4: You’re Paying a Lot Less for Phones!

    Up front you are. The iPhone 5, for example, costs $99 down on T-Mobile but over those 24 months you’ll be paying $579 for the hardware. For not much more money you can buy an unlocked iPhone 5 ($649) and take it to AT&T or T-Mobile. Worse, T-Mobile is overcharging customers for the Nexus 4. You can pick up the 8GB version through the Google Play store for $299, while the T-Mobile version costs $49 up front but $457.99 when paid in full.MORE:10 Smartphones You Should Buy Now

  • 5White Lie No. 5: Our 4G is Better Than Their 4G!

    At T-Mobile’s launch event I was very impressed by the data speeds delivered by the Galaxy Note 2 and HTC One, with downloads ranging from 30 to 50 Mbps. The iPhone 5 was a little bit behind that. But this was on an unloaded network. T-Mobile says it has 50 percent more bandwidth than AT&T, which means less congestion, but seven launch cities puts T-Mobile way behind AT&T’s 161 markets and 486 for Verizon Wireless.When you’re outside of T-Mobile’s LTE coverage, the carrier offers faster HSPA+ 42 speeds compared to AT&T’s 21 Mbps HSPA+ fall-back network. However, I’ve tested a number of T-Mobile phones in recent months that fall back to 2G in New York City and New Jersey. 2G! That never happens on Verizon and AT&T now, at least where I travel.