A small sampling of the issues:
Everything is 256 bits wide, including the "byte" type. This means that whilst byte is valid syntax, it will take up 32x more space than you expect. Storage space is extremely limited in Solidity programs. You should use "bytes" instead which is an actual byte array. The native 256-bit wide primitive type is called "bytes32" but the actual 8-bit wide byte type is called "int8".
Strings. What can we say about this. There is a string type. It is useless. There is no support for string manipulation at all. String concatenation must be done by hand after casting to a byte array. Basics like indexOf() must also be written by hand or implementations copied into your program. To even learn the length of a string you must cast it to a byte array, but see above. In some versions of the Solidity compiler passing an empty string to a function would cause all arguments after that string to be silently corrupted.
There is no garbage collector. Dead allocations are never reclaimed, despite the scarcity of available memory space. There is also no manual memory management.
Solidity looks superficially like an object oriented language. There is a "this" keyword. However there are actually security-critical differences between "this.setX()" and "setX()" that can cause wrong results: https://github.com/ethereum/solidity/issues/583
Numbers. Despite being intended for financial applications like insurance, floating point is not supported. Integer operations can overflow, despite the underlying operation being interpreted and not implemented in hardware. There is no way to do overflow-checked operations: you need constructs like "require((balanceOf[_to] + _value) >= balanceOf[_to]);"
You can return statically sized arrays from functions, but not variably sized arrays.
Arrays. Array access syntax looks like C or Java, but array declaration syntax is written backwards: int8 creates 5 dynamic arrays of bytes. Dynamically sized arrays work, in theory, but you cannot create multi-dimensional dynamic arrays. Because "string" is a byte array, that means "string" does not work.
The compiler is riddled with mis-compilation bugs, many of them security critical. The documentation helpfully includes a list of these bugs .... in JSON. The actual contents of the JSON is of course just strings meant to be read by humans. Here are some summaries of miscompile bugs:
In some situations, the optimizer replaces certain numbers in the code with routines that compute different numbers
Types shorter than 32 bytes are packed together into the same 32 byte storage slot, but storage writes always write 32 bytes. For some types, the higher order bytes were not cleaned properly, which made it sometimes possible to overwrite a variable in storage when writing to another one.
Dynamic allocation of an empty memory array caused an infinite loop and thus an exception
Access to array elements for arrays of types with less than 32 bytes did not correctly clean the higher order bits, causing corruption in other array elements.
As you can see the decision to build a virtual machine with that is natively 256-bit wide led to a huge number of bugs whereby reads or writes randomly corrupt memory.
Solidity/EVM is by far the worst programming environment I have ever encountered. It would be impossible to write even toy programs correctly in this language, yet it is literally called "Solidity" and used to program a financial system that manages hundreds of millions of dollars.
That's kind of a feature. Sure you can use decimal floating point (but never, NEVER use the common binary float for money), but storing integers of the minimum currency unit (e.g. cents) (typically wrapped in a Money class in OO languages) is also a good option.
Although one fairly well-known package, produced by a place I once worked briefly, which (when I worked there) internally used doubles for all money values, wrapped in a class that re-rounded the results every so often. No, really.
I pass no judgement on what belongs on Ethereum. I know from their website that they advertise it as a platform for general app programming and even implementing entire autonomous businesses. It clearly cannot support these things.
We solved that for floats like 10 years ago. Let alone the fact there are better formats, like posits, or fixed point numbers, that also solve this problem very easily.