I find this site to be extremely helpful when Im looking for genomic information on unknown mouse or human genes. Also I use it to create exon maps for genes of interest.
Yes, UCSC arguably provides the top genome browser (for certain genomes). Some might say that the EnsEMBL browser is more functional albeit perhaps a bit less intuitive. I use each for their various strengths and weaknesses (e.g. if you want to do anything in high-throughput, the EnsEMBL API or BioMart utility are extremely useful).
Has anyone else noticed the UCSC browser has been pretty slow (often timing out) over the past few weeks?