The Yamaha SHS-500 is a versatile and fun, compact keytar. This instrument has some advanced features like simultaneous USB audio and MIDI transmission, so take a look at the manual and serious YouTube tutorials. Avoid the wacky demos and uneducated reviews as they are very misleading. This has small keys like Reface series. The unit feels comfortable strapped on and the controls are accessible. Limited onboard sounds are good and the unit has a decent filter and effects. One downside is there is no volume control for external devices, just the onboard sounds. I'm using it as a wireless controller for iOS apps and latency is a non-issue. I recommend installing the Yamaha Chord Tracker app and establishing a link before trying to connect Bluetooth with other apps. If you just want to use it as a MIDI controller then don't hit the "Jam button." Jam works with your songs imported to Chord Tracker, but it's not what I am interested in and it's an optional feature. Too bad that it cannot transmit MIDI master volume, but overall it's a fun keytar...so 4.5 Stars.