Here's a list of recent changes that might possibly break backward compatibility. If you have a "weird" problem, chances are some default settings changed between revisions.

• In commit 297, support for pairs with same opening and closing delimiter was added. That is, pairs like $$ in latex are now recognized as any other sexp. There are still some problems in modes where the delimiters serve multiple purposes, like * in markdown (unary list item, binary emphatic text). Use the variable sp-navigate-consider-stringlike-sexp to set the major modes where these should be supported. latex-mode is added by default.
• In commit 270, an experimental support for SGML tags has been added. You can use all the operations on these as if they were normal paired expressions. Use the variable sp-navigate-consider-sgml-tags to set the major modes where tags should be supported. html-mode is added by default.
• In commit 149, the default configuration has been pushed to the default build. You might want to spent a few minutes adjusting your own personal config and remove the unnecessary parts. If you feel that some settings should be added (for example you use some mode that would reasonably fit the defaults), comment in the [Issue #20] thread.
• Very important option sp-navigate-consider-symbols has been added. Setting this to t will make spartparens consider symbols and strings as balanced expressions. That is, something-like-this will be considered as balanced expression enclosed by pair of whitespace characters. This emulates the original behaviour of forward-sexp and it is recommended you set this option to t for best user experience. From commit 130 this is set to t by default!
• From commit 118 forward, strings (as defined by mode syntax-table) are treated as other paired expressions. This means you can use sp-up-sexp, slurping and barfing on strings the same way you would use it with any other expression recognized by sp-get-sexp.