-Estimated Trophy Difficulty: 8/10 This varies for everyone though depending what instrument you use and your skill with it.
-Offline: 49 Some are much easier done online though
-Missable trophies: None
-Do cheats block trophies?: Yes
-Approximate amount of time to Platinum: 50-150 hours. If you've played other music genre games like Guitar Hero and can play expert this will come to not much more of a challenge. If you've never touched a music genre game then it may take well over 100 hours of practice just to be able to play expert. Then to be able to play expert on all instruments even if its on their easiest song will take a long time. If your going to pick this game up strictly for trophies i would stay away unless your prepared for it.
If this is your first time playing a music genre game then PLAY THE TUTORIALS. The tutorials give you the basics of the game and tell you what you'll need to get started and can be very helpful to a new player. You can find tutorials for all instruments under TRAINING then TUTORIALS. This game takes practice. You will need to be able to play and beat every song on expert for a certain instrument and there are some pretty hard songs so this may take you awhile. For tricky parts of a song you can go to practice mode where it lets you go to a specific part in the song instead of playing over and over to get to one part. To get there go to TRAINING then PRACTICE.
Here's a few of my personal tips.
Guitar: Hammer ons can be your best friend or your worst enemy. They can save you so that your hand can take a break for a second and it can really help with tricky note sequences. It can be your worst enemy though because sometimes you'll go for the hammer on and you'll miss the note. You dont have to be spot on with hammer ons but you need to be very close. On very fast sections strum up and down instead of just down as it is much easier to strum faster this way. If you feel your close to a gold star and its near the end of a song start to whammy. Whammying gives you more points though not much you never know it could be just enough to put you over the edge and get that gold star rating.
Bass: For the bass the songs generally have the same sequence over and over or something close to it. Its the same as the guitar in the fact that whammying gives you more points and there are hammer ons though not many for bass. There is a lot more chords as a bassist (the double and triple notes) so you might have to practice the song a couple times to get your double and triple note hitting skills good enough. Generally bass is easier than guitar but on some songs like Visions it has the same exact notes as the guitar. Or sometimes they are even harder than guitar for example Ace of Spades' bass notes to me seem like a very random pattern and hard to pick up. I find most songs on the bass much easier than guitar though.
Drums: The footpedal notes (long orange ones) are normally the same pattern or close to it throughout the song. If you get stuck on a song take baby steps with it. First learn the footpedal and its pattern. Then after you've got that part down start to hit the red, blue, yellow and green notes. You can buy a second footpedal for the really fast footpedal songs (mostly the metal songs at the end). I personally do not own one but numerous people told me once they got used to using a double footpedal it made it so much easier.
Vocals: Though saying the words to the song makes it fun its not necessary, I repeat SAYING THE WORDS IS NOT NECESSARY. Though it makes it more fun at parties and around friends for songs like So What'cha Want it makes it much harder. You can simply hum the tune of the singers voice and it will work.
Overdrive and you.
Overdrive is a very valuable asset you will notice while progressing through the career. Some songs cannot be gold starred without using your overdrive in the right place. You get overdrive by hitting the white notes in a song. You must hit ALL of the white notes to get overdrive. When your playing as guitar or bass and the overdrive is placed on a long note whammy like you've never whammyed before because you get overdrive everytime you whammy that note. Guitar and bass can use overdrive whenever they want by tilting the guitar controller up into the air or by pushing the select button located next to the strum bar. The drums and vocals on the other hand can only use it at certain points. Once you get overdrive with the drums you will see a drum fill section where you can play whatever you want and then you must hit the green drum at the end to deploy overdrive. The drum fill looks like long streams of (going from left to right) red, yellow, blue and green that take up the whole note chart. For vocals you get overdrive by playing the overdrive section of the chart right and you must either hum or hit the microphone with your hand when your note chart goes gold to deploy overdrive. Many trophies require you or just help to have overdrive.
[PST would like to thank legndorock for this Road Map]