What is the problem with IOTA?

Could you please elaborate on the challenges or issues surrounding the cryptocurrency IOTA? I'm curious to understand the key problems it faces and how these might impact its future prospects and overall performance in the crypto market. Are there any specific technological challenges, scalability issues, or security concerns that are commonly raised about IOTA? Also, how does it compare to other major cryptocurrencies in terms of these challenges, and what strategies might be implemented to overcome them? I'd appreciate a detailed yet concise overview of the main issues surrounding IOTA.