Hey @moratar,
This is a great question, especially for people who are new to Zcash or cryptocurrency in general, as the task of comparing hundreds of different coins can seem quite daunting at first.
Firstly, as @garethtdavies noted in his reply, scalability is a general problem common to all cryptocurrencies, including both Bitcoin and Ethereum. At Devcon3 last month, Vitalik Buterin gave a talk about sharding and the future scalability of the Ethereum blockchain, which I encourage you to research if you want to learn more.
Now I’ll address the heart of your question, which is asking if Zcash is better/more useful than other cryptocurrencies, or just a Bitcoin clone with no real utility. The answer is that Zcash is extremely unique, and to date, the only cryptocurrency that solves the fungibility problem. Here’s a link to a previous reply I made which briefly explains how Zcash solves fungibility.
To be clear, there are still additional steps that users must take in order to properly wash your ZEC using z-addresses, such as not sending identical amounts in and out of your z-address (See this blog post for a more detailed explanation). However, when used correctly, Zcash is the only coin that is provably private and thus provably fungible.