I smell cash-in, must be Guitar Hero Encore...
Graphics - GHE's graphics are pretty much the same as GH2's, with minor changes such as the colors in the venues and the characters' costumes. The characters' costumes a done fairly well to give you that 80's vibe, but the venues are severely lacking.
Gameplay - The gameplay is no different than GH2 and still features the same HO/POs among other features.
Sound - This is the most important part, right? The sound quality is nothing below excellent, but the setlist has left something to be desired. While consisting of great 80's tracks such as Round and Round by Ratt, 18 and Life by Skid Row, and Electric Eye by Judas Priest, there are several other songs that are less well-known and are kind of, dare I say, annoying to play through. Some of these lackluster tracks are Because It's Midnite by Limozeen, What I Like About You by The Romantics (who are currently trying to sue Activision), and Ballroom Blitz by Krokus, I mean, come on?! What ever happened to Megadeth, Slayer, Van Halen, and Metallica in this time period? But, alas, this is a cash-in afterall.
Overall, Guitar Hero Encore: Rocks the 80's is one of those installments that just plain reaks of cheap cash-in, making it definetly not worth the fourty bucks.