There is also a perl script called TrinityStats.pl in the 'util' directory that will give you stats for genes, transcripts, reconstruction size and N metrics. Use as 'perl /path/to/your/install/util/TrinityStats.pl your_assembly.fasta'
There is a perl script in the Trinity util folder called "TrinityStats.pl"
You can use it as follow:
perl /trinityrnaseq-2.2.0/util/TrinityStats.pl /folder2file/Trinity.fasta
Edit: I see @st.ph.n just commented the same solution! Nevermind...