My verdict: the reference SEO suite for pros.
Semrush is complete and powerful, with a price that reflects its leadership position. The all-in-one suite to dominate SEO and content marketing. Semrush gives you access to everything: keyword research, SEO audit, backlink analysis, position tracking, competitive analysis, and even advertising (PPC). It's the reference tool for SEO pros. The problem? The price: $129/month for Pro, and it goes up fast. The interface is dense (many features). If SEO is strategic for you, it's a worthwhile investment.
What I like less: the high price, the sometimes overwhelming interface, and the fact that for simple needs, it's overkill.
My advice: Semrush is worth the investment if SEO is an important acquisition channel for you. For basic needs (a few keywords to track), cheaper alternatives are sufficient. Use the free trial to see if the advanced features are really useful to you.