Any tips on buying a Roku box?

Mr Peabody had her boy Sherman over today to help with a few technical issues. One was that my TV has stopped letting me do streaming. Several people, including myself, have diagnosed it as having stopped – that cannot be fixed. I am loathe to buy a new TV and Sherman suggested I buy a Roku box for streaming which sounds great.

Any advice before I buy? (And yes, I am soliciting advice.)