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This is the parade of Excel workbook protection tools!
I have focused on the base features of the products which affect the security and misbehavior of protected solutions.

PROS: A newbie in Excel cannot reach the content of the protected workbook.
CONS: The product is programmed in vba. The tool relies on standard MS Excel protection methods like workbook/worksheet protection and vba project password plus the vba code obfuscating. You do not need to be C programmer to pass over such protection.
“For maximum VBA security, use the Microsoft Excel 2007-2010 format (".xlsm") and add a VBA password to your file which contains random alphanumeric characters and is at least 15 characters long.”
This advice from their help file just kills me!
Looks like the guy who wrote this product has been learning vba programming by the way. 
SUMMARY: Junk. The product is on a student project level.

Spreadsheet Sentry:
PROS: The tool is programmed in C++, uses strong encryption to protect formulas in cells. In protected solution formulas are encrypted, stored in cells and not readable.
CONS: Takes WAY too much time to encode a workbook even for middle size model.
Protected solutions work veeeery sloooow. Calculation time is wasted for encryption/decryption every formula in calculation chain.
The tool doesn’t protect VBA code.
SUMMARY: Protection works. The tool appropriates for small workbooks without VBA macros.

This is the most controversial product in the review. After the first glance I wanted to give “the perfect” mark, but see what I have finally found ….
PROS: The tool is programmed in C++. In protected solution everything works like in original workbook. Average user cannot see formulas in cells and vba code in protected workbook. Protects xla files. Lots of features.
CONS: The product uses unmodified, original workbooks in protected solutions and relies on hackers’ methods to take customer away from seeing the content of the workbook (Hooks Excel windows and blocks Excel’s COM objects methods calls). The tool is trying to stub all Excel’s security breaches, which is impossible with an unmodified, original workbook.
When a protected solution has been started on an end customer computer, the spreadsheet becomes as unprotected as newborn baby.
5 lines of C code extract the original workbook from the protected solution, doesn’t matter whether it’s xls or exe file.
To prove the vulnerability of LockXLS solutions, just e-mail a protected solution to WhiteHatXL at yahoo dot com , the original workbook will be returned.
SUMMARY: Fake. This product is not for a workbook protection.

Secure Calc (former ExcelShield):
These guys have ignored my requests for a trial version, so I have evaluated the product by the simple example from their site—It may work different for complex spreadsheets.
PROS: The tool uses strong encryption for formulas, removes formulas from cells, has calculation engine to evaluate protected formulas.
CONS: Engine is written in .NET environment in pure managed code, which is not good for a protection tool. Source code may be reached by Reflector and reverse engineered. No VBA Protection.
The calc engine is not included into protected solution and should be preinstalled on customer computer separately. Each time, after typing new data into cell, the customer has to click the ‘Calculate’ button, which is available through the main Excel menu. This is very annoying.
SUMMARY: Protection works. It looks good enough, if you do not need to protect vba code.

xCell Compiler:
PROS: The tool is programmed in C++, compiles formulas into binary code and removes them from cells, protects vba code. Has calculation engine to evaluate protected formulas. Has a lot of features.
CONS: The tool has limitations declared on their web site. A protected solution doesn’t support adding/removing columns/rows/sheets. Sorting for ranges with formulas doesn’t work.
SUMMARY: Protection works. Good, if you do not use features mentioned in limitations.

Excel Translator:
I was unable to get the neither trial version nor example of protected workbook. Very “strong” protection!

Converter XL to Exe:
PROS: Free, Free, Free!!!
CONS: This tool is not for a workbook protection.

I hope it will help someone….