There are many different ideas on the best way for adults to learn a foreign language. Much depends on the student, their goals, and their self-discipline.
I learned Spanish as an adult. I am now fluent at a professional/business level. About 10-15% of Tagalog is Spanish, and the spelling of Tagalog words are all based on Spanish sounds.
I learned to read Thai. I can write some, but my vocabulary is very small. 90% of my Thai came from taking private one-on-one classes while living in Thailand for 6 months. I studied some Tagalog, some Korean, and some Thai using Rosetta Stone.
If you just want to learn some Tagalog to get around as a tourist, enough people speak excellent English in the Philippines you will probably never be able to use it. The Filipinos who don't speak English will typically avoid speaking to you, even when you try to speak Tagalog. Regardless, an immersion product, like Rosetta Stone, is probably not as useful because much of the vocabulary and context is not related to what you will want to know (do you really need to say the boy is under the soccer ball?).
If you want to seriously learn the language to be able to carry on conversations, commit early and realize there is far more work involved. To really practice Tagalog, you need to go to less savory parts of Manila, or plan on getting outside of Manila, Cebu, away from the red light districts in Olongapo and Angeles, and avoid the resort areas like Puerta Galera and Boracay. To really use Tagalog, you need to go where those who don't speak English will make an effort to understand you.
My first consideration was alphabet phonetics. This was easy since spelling is based on Spanish phonetics using the Roman alphabet. For other languages, like Thai, consistent pronunciation based on Romanized phonetics is doomed to fail. This is probably true of Korean and other phonetic alphabets.
My second consideration is note taking. As adults we want to take notes to help remember key points. If you take the notes in English, you are handicapping yourself. This is more difficult, and far more important, in languages with their own script.
My third consideration was I knew learning translation would create a permanent handicap. Early on, translation is easier, later on translation must be unlearned as it stilts actual conversation and thinking. You just can't translate fast enough. Even now, being fluent in Spanish, translating gives me a headache and frustrates me. I either have a conversation in Spanish, thinking in Spanish, or I have a conversation in English thinking in English. If I know a word in one language and not the other, my whole train of thought is derailed. Avoiding learning translation is where Rosetta Stone shines.
The idea of Rosetta Stone is sound. If you are disciplined enough to do the lessons regularly, you will expand your spoken vocabulary rapidly. You will remember what you learn. For reading and writing, Rosetta Stone is limited. I doubt it will do much for reading and writing with non-Roman scripts. Their voice recognition is really weak, just like all other applications. Learning to speak requires real speakers in their native environment. Regardless, disciplined study will yield results with Rosetta Stone.
Rosetta Stone is very expensive. Competing products like L-Lingo or products using different methods like Pimsleur, TellMeMore.com, Assimil, or Fluenz (supposedly the best, but only in a few languages) are a fraction of the cost of Rosetta Stone. Many of the different methods will work better than Rosetta Stone for some. L-Lingo offers a free trial. Assimil is translation based. Pimsleur is hard to describe, but has a very good fluency success rate (supposedly). Look up Fluenz also, as the method and reviews suggest it is very effective in the few languages they offer.
Besides cost, what is the other drawback to Rosetta Stone? The drawbacks are legion.
Version 2 is good. Version 2 is how Rosetta Stone grew into a powerhouse. The voice recognition is very primitive. Version 3 is a refinement of version 2 with improved continuity, a smoother interface, better quizzes, and the ability to get rid of the stupid "must have CD with you at all times" limitation. You can also advance or return to the exact spot where you left off earlier.
Unfortunately, Rosetta Stone dropped support for Version 2. Even though they were selling version 2 from their own website in 2012, they dropped support. Mac users are especially impacted as Mac OSX Lion will no longer run PPC apps, and Rosetta Stone never ported Version 2 to Intel. So, if you bought Version 2 in 2012 to use on a Mac, you were ripped off by Rosetta Stone. Join the crowd.
Windows users should not be too smug about the situation, as the end of Version 2 support means your product will have all sorts of issues too, unless you downgrade to WinXP.
Version 3 is supported on current platforms (to the extent Rosetta Stone supports any product). Version 3 is easily the pinnacle of the Rosetta Stone application. Given so many users prefer version 3 to version 4 though, don't be surprised if they pull a Microsoft and force users to their new product.
Total 4e, is a disappointing retrograde of Rosetta Stone. To be fair, if you are always connected -- literally 100% of the time, never a lost packet -- and live your life via social media, Total 4e might work. Don't expect to use the highly touted iOS apps on your iPhone or iPad though unless you are connected 100% of the time with those devices also. The whole idea of quickly practicing while in line or waiting in at a soccer practice...yeah, that doesn't conform to the Rosetta Stone licensing model.
Speaking of which, Rosetta Stone now has two components and two licensing models. There is the software application and the online social media part. The application can be run as long as they support it on current platforms. The online social media component is now on a subscription basis. You pay for every month in which you want to participate. You can still use the app on your computer, but you just paid a premium for online access you aren't using unless you continue to pay the subscription.
Given there are many free or lower cost websites where learners can interact and practice language skills, why pay Rosetta Stone a monthly premium for less content? Therein lies the reason so many people look at Total 4e and then try to find version 3 before supplies run out.
How about another suggestion?
Try L-Lingo. L-Lingo uses a very similar learning model to Rosetta Stone. The interface actually has more features than Rosetta Stone and you can customize the interface to use Roman phonetics or native script. They have iPad and iPhone/IPod Touch iOS apps which you can use on a plane, or anywhere else, with or without Internet access. Best of all, all of their programs together (Win or Mac desktop, iPad, iPhone/iPod Touch) are less than half the cost of Rosetta Stone Level I.
L-Lingo specializes in Asian languages. They are probably a superior option to Rosetta Stone Total 4e for most users. L-Lingo offers a free trial for their desktop application, and also for their iOS applicastions for some languages.
There are other good options listed above, particularly Fluenz and Pimsleur which use different methods. Be sure to check them out before buying anything published by Rosetta Stone.