Really depends what you are after. I have the 4660 Ultra for my main viewing because of the ethernet and the USB which I initially used as my beginner "media server". All my other rooms have Premieres and a RokuTv in the kitchen. If you are happy with the performance of your current device and don't need the extra speed and features the Ultra offers, then I would say no. If you want faster speed or you have a higher resolution TV that isnt supported by your current device, then yes. It depends on your setup and what you need or are after. It is a good buy at $80 which is the normal sale price, and $100 for regular pricing.
These devices go on sale from time to time (this is not a 1-time offer you are seeing). It may be another couple of months before the sale is on again, but it will be. I generally like to buy the devices in a store as opposed to online, but just personal preference. Figure it will be easier if I have to return for any reason.
To date, have yet to replace any of my devices, but have bought more of them for friends and family.
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941